Category: Critical Thinking

Can teachers use multiple choice to test critical and scientific thinking in the new science curriculum? The short answer is, yes, teachers can use multiple choice to test critical and scientific thinking in the new science curriculum. However, this requires some modifications to how teachers write their multiple choice questions.

 

In our previous post, we wrote how we can use more critical thinking skills in multiple choice questions by changing how we write the answers and prompts for our questions. Unfortunately, this has its limits. That is, if teachers continue to ask the same old multiple choice questions that rely on recall and memorization, then simply changing the answer choices isn’t going to make a big difference. What teachers need is to start asking better multiple choice questions. Therefore, what are examples of good multiple choice questions we can ask that require critical and scientific thinking?

 

We suggest using more case studies in multiple choice tests. Case studies provide students with real data and contexts to apply their knowledge. Thus, they are great opportunity to test critical thinking. For example, questions for our REAL Science Challenge Contests are always based on case studies. And, students find them challenging because students aren’t used to questions that require them to apply their knowledge in a given situation.  Unfortunately, case studies are not always easy to find or readily available. Thus, teachers need to create their own. In this post, we aim to help teachers create their own case studies for multiple choice exams. We present 3 types of case studies teachers can use and the types of questions that teachers can use for each type. A case studies outline is available for download at the end of this post.

 

Easy Case Studies for the scientific thinking

Want to make multiple choice test questions that use case studies to engage critical and scientific thinking? We suggest writing case studies that focus on one of three themes: (1) experimental design analysis, (2) experimental results analysis, and (3) multiple hypotheses analysis. We outline the three case study themes below.

 

1. Experimental Design Analysis

In these case studies, students are responsible for analyzing how an experiment is setup and how changes to the experimental setup can change the results. Students are typically given:

 

• Some background information regarding what the experiment is about.
• The experimental procedure, which includes the independent and dependent variables as well as some important controlled variables.
• Two or three different variations to the same experiment.
• Results in the form of tables or graphs for all variations to the experiment.

 

Questions for experimental design analysis case studies include:

• Identifying independent, dependent, and controlled variables.
• Predicting what can potentially occur if there are changes to any variables.
• Identifying or developing testable hypotheses
• Predicting hypothetical conditions that may provide similar experimental results
• Predicting future results under certain conditions.

 

Sample Case Study: Passage 1 in REAL Science Challenge Vol 2 Contest 4 (available for download at the end of the post).

 

2. Experimental Results Analysis

In these case studies, students are responsible for analyzing experimental results and applying such results in other scenarios. Students are typically given:

 

• Some background information regarding what the experiment is about.
• Multiple graphs and tables showing different relationships between variables in the experiment.

 

Questions for experimental results analysis case studies may include:

• Interpolation and extrapolation of lab results
• Determining the conditions that produce a given or range of results.
• Identifying conditions that may produce a given results
• Drawing claims or conclusions from experimental results.

 

Sample Case Study: Passages 2 and 4 in REAL Science Challenge Vol 2 Contest 4 (available for download at the end of the post).

 

3. Multiple Hypotheses Analysis

In these case studies, students are responsible for comparing and contrasting the many hypotheses that may exist that explain the same scientific phenomenon. Students are typically given:

 

• A scientific phenomenon where there may be multiple hypotheses that explain the phenomenon.
• Details regarding two or three of the most popular hypotheses.

 

Questions for multiple hypotheses analysis case studies may include:

• Determining which hypothesis is supported or refuted if given new evidence.
• Predicting future experimental results if one of the hypotheses was deemed correct.

 

Sample Case Study: Passages 3 in REAL Science Challenge Vol 2 Contest 4 (available for download at the end of the post).

 

Wrap Up

If teachers want students to apply their critical and scientific thinking skills on a test, case studies are a great resource. And, case studies work for multiple choice too (so long as the answers options are written well too – refer to post #36 for details). Unfortunately, case studies take time to create from scratch. Hopefully, by following the suggestions above, the learning curve for writing good case studies will not be as great. Of course, there is also the question of where to find good sources of information for case studies, which we will leave for a future post. Join our newsletter if you want to stay up to date with our posts or if you want to know when our follow up post to this resource will happen. And, click the link below to download the handouts (case studies outline and sample passages) for this resource. Lastly, leave a comment below or share our post with your friends or colleagues.

 

Until next time, keep it REAL.

 

Resources

Handout(s): 37 – Case Studies Outline

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Does the development of new science curriculum like the Next Generation Science Standards mean multiple choice questions are no longer acceptable? Does it mean that short answer or essay/written responses are the only responses that assess critical thinking? The short answer is no. Written responses are not the only way to assess critical thinking. Multiple choice can assess critical thinking too. And, I believe multiple choice can still be a part of your NGSS science test – by writing critical thinking multiple choice tests. So, what do you need to do to have multiple choice tests align with the skills that new curriculum is trying to stress?

 

One change teachers can make is by changing the types of multiple choice answers in our tests. A common argument against multiple choice is that one can get to the answer by eliminating obviously wrong options.  Thus, as detractors will argue, a multiple choice test is no longer a test on knowledge but instead an exercise in test writing. I agree with this argument. A multiple choice test should not be a test about testing but rather a test about content knowledge and understanding. To integrate multiple choice into the current curriculum, we need to make students think about each option in a question by writing better responses. We outline a few strategies below to help write better multiple choice responses that promote more critical thinking. Handouts – which will include a sample passage and critical thinking multiple choice examples – are available for download at the end of this post.

 

Multiple Choice is Critical Thinking

Here’s the big idea: answering good multiple choice question is critical thinking. Why?  Because, for a student to read each multiple choice answer to assess whether one option is THE answer among all the options requires critical thinking. However, this is the ideal. Unfortunately, a lot of multiple choice answers are written so that students rely merely on recall or never require critical thinking at all.

 

This problem is not impossible to solve. But, it takes time and practice. Personally, I’ve written multiple choice questions for all our REAL Science Challenge contests – and I am only starting to be comfortable writing good multiple choice questions that require students to think critically. Below are some of the strategies I’ve researched and adopted in writing the multiple choice options to our problems. I hope you find them useful too.

 

7 Tips to writing Critical Thinking Multiple Choice 

 

Strategy 1: Answers must all sound plausible.

If each option sounds plausible, then students will take time to think about and distinguish the differences between each option.  Obviously phony answers may be fun to include as a multiple choice option, but those options can also be easily eliminated (without thinking critically) as not the answer.

 

Strategy 2: Have more than 1 right answer.

This strategy is used on Advanced Placement (AP) exams. And, on REAL Science Challenge contest questions, questions with more than 1 correct multiple choice answer are extremely challenging for students. This is no surprise. Most students look for 1 correct answer and then stop. But what if there were more than 1 answer? Then, students would need to check all options to see if any other option would also correctly answer the multiple choice question.

 

Strategy 3: Instead of restating the textbook, provide alternate examples.

By providing the right option as an exact copy of what’s stated in the textbook, students can identify the answer strictly by recall. To challenge the mind a little more, provide options that are new or analogous examples. This way, students need to at least analyze to see if the new examples fit with what was stated in the textbook.

 

Strategy 4: Have answers that include a justification

Students can choose what appears to be a correct answer. But, can they then justify their answer?  By adding justifications, students will need to choose the correct response and understand why the option is correct too.

 

Strategy 5: “All of the above” or “None of the above” cannot be an answer

Similar to the problem with including fun and phony multiple choice options, both “All of the above” and “None of the above” can easily be eliminated without using critical thinking. For example, so long as one of the options is not correct, this automatically eliminates “All of the above”.

 

Strategy 6: Answers should not have words like “never” or “always”.

As the old mantra goes, “never say never”. Words like “always” and “never” represent extremes, which are clues for students to eliminate the multiple choice option.

 

Strategy 7: Keep the lengths of each multiple choice answer the same.

Unfortunately, students are able to pick the right answer (or eliminate wrong ones) simply because they are overly wordy. Thus, this becomes an exercise in test writing instead of knowledge assessment. By keeping the length of all answers the same, we close this loophole.

 

Wrap Up

Multiple choice questions get a bad wrap from new curriculum for not being able to assess critical thinking. This is not without reason: lots of multiple choice questions rely on simple recall or knowing some test writing strategies. This is unfortunate because multiple choice questions can assess a greater breadth of content than written response. And, done correctly, multiple choice can assess critical thinking skills too. Perhaps, with a few improvements, critical thinking multiple choice questions can help return multiple choice tests to being a good assessment option. Click the link below to download the handouts to this post. Our handouts include a quick checklist of the strategies above as well as a sample passage and multiple choice examples. Please help us share our resource and website with your peers too!

 

Until next time, keep it REAL!

 

Resources

Handout(s): 36 – Critical Thinking Multiple Choice Handouts

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Density is an awesome property of matter. Density can help identify unknown materials (circa Archimedes and the Gold crown). Differences in density determine the relative position of objects (ie. Which objects sink and which objects float). Unfortunately, students too often learn that density is just a formula. A calculation. That it’s not applicable to the real world. Sure, ships and boats are applications of density at work, but it’s hard for students to realize all the connections. Students may wonder, Yes, there are lots of air pockets and empty spaces in boats that make it less dense than water, but metal is also a very heavy dense object too.” So, what’s another way we can teach density so that students can see the connection between theory and real life? What density lab can we do?

 

Breaking Bread

When I first started teaching, I was told that students won’t remember what was taught, but they’ll remember what was done. Two years ago, I taught students about density by baking different types of bread in science class. And, today, my students still remember it (the bread making part of it, that is). The activity itself is meant to be a density lab with an inquiry twist, but it can be modified to be a single classroom activity – depending on class needs and time restraints. At the end of this post, I provide a checklist for my original bread density lab along with some modifications to make it go faster and easier.

 

Bread is a great medium to use to teach density because it is something everyone can relate to and there is a a lot of science behind baking. And, bread is also very easy to work with. Because bread can be cut into rectangular prisms or cubes, students can measure the volume and mass and calculate the density easily. And, because students get to see the air pockets in bread slices, students can easily see that less dense bread typically has more air pockets and more dense bread is more packed together. And, that’s the general idea behind density, isn’t it? Density is basically how much mass (or material) is packed into a given volume. Bread easily demonstrates this point.

 

Our own bake-off

In the original version of the bread density lab, students bake a regular loaf of white bread – for which I provide the recipe. Then, they cut into the bread, cutting out a nice rectangular prism for which they measure the volume and mass and calculate density. This is “control loaf”. Next, students need to take one ingredient used to bake bread and modify the amount used. Students need to make a hypothesis, for example, if more sugar is used, then the density of the bread will decrease. Then, students bake bread again using the same recipe as before with one exception. This time, they use a modified amount of whatever ingredient they decided to study. They find the density of this loaf of bread and compare to the control loaf. And, the cycle can repeat itself depending on how much time there is. In our case, the students made 3 loaves of bread (including the original). And, they loved every aspect of it (even the eating part when they took the bread outside science class).

 

Field Notes

• Have students make qualitative observations and conclusions regarding the bread. How do you know this bread is less dense or more dense? What is causing this bread to be more or less dense? Explain using CER (Claim, Evidence, Reasoning).
• Make this a cross curricular activity. I was lucky to work with one of our Home Economics teachers, who loved what I was doing and didn’t mind helping me out with the supplies and using the oven. This makes everything much, much easier. I can focus on the science component of things (ie. scientific method, observations, etc.) while the home economics teacher can focus on the hands-on piece. Also, administrators love it when departments work together to make learning more hands-on and applicable for students.
• For a one day activity, I would buy various types of bread from the grocery store (rye, whole wheat, barley, white, etc) and have students find density and compare instead of baking my own bread.
• To bake quicker and more efficiently, consider getting a bread maker. Some bread makers allow you to literally dump in ingredients, set, and forget. This is a great way to demo the bread making. Bake one loaf one day, then change one aspect and bake the next day again. It’s fast, and some bread makers can be quite inexpensive.
• Another way of doing this lab is to have students bake muffins. A muffin tin has anywhere between 6 and 12 wells Thus, students can bake 6-12 different variations of the same recipe at the same time. And, their densities can be compared right after.

 

Wrap Up

Density can be an abstract idea. It doesn’t help that some students just memorize the definition and formula. But, when students see it in the ordinary, everyday things (like bread!), it makes it more concrete. More real. And, students remember if so much more. And, long after they’re graduated, hopefully, they’ll remember what a great time they had in science class too. Click on the link below to download a copy of our handouts.

 

Until next time, keep it REAL.

 

Resources

Handout(s): 15 – Bread Density Lab Checklist

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What are some science skills students need to know how to do? I can sum it up in one statement: we want students to be able to think (and do) like a scientist. Therefore, science students need to know how to design and run experiments, collect and analyze data, draw conclusions and defend them. (Refer to curricular standards here) All the content we teach – KMT, cell division, continental drift, Newton’s laws – they are just avenues through which students practice science skills.

 

One problem I run into is not knowing what skills students need help with. Do they know what an independent or dependent variable is? How about the concept of a control with them? Do they know how to read a graph (and draw conclusions from it)? Typically, teachers analyze student lab reports for clues. Or, we can collect notebooks or assignments. But, students can plagiarize lab reports (or assignments). Or, students don’t hand them in. And, lab reports take time to mark – even if you are just marking one or two questions. Is there a way students can quickly demonstrate and practice science skills?

 

Not your ordinary quiz or test

We believe so. In fact, multiple choice tests like the science component of the ACT (American College Test) already test for science skills like analyzing graphs and drawing conclusions. However, the ACT is meant for Grade 12 students who are graduating and applying for college. What about students in Grade 8 and 9, who may need more help developing the science skills that will help them for the rest of their high school career? We developed a quick 10 minute activity that has students read a summary of a real lab experiment and then answer a set of multiple choice questions that require students to apply and practice science skills. It is inspired by ACT and MCAT (Medical College Admissions Test), which measure how students apply science skills. Our activity is meant to help students and teachers identify and practice science skills that may need attention. We outline how we did it below, but you can also download our activity (ie. an actual research study that studies whether water immersion after high-intensity exercise improves recovery) at the end of the post.

 

How we do it

1. Go online to find interesting science research articles.

Our two favourite websites right now are the Public Library of Science and Research Gate, both of which provide free full length research articles for the public to use and redistribute. Both sites allow you to search their database for articles too. EBSCO is great as well, but articles may require purchasing or licensing if you decide to distribute or post on a website. Newsela and other student news sites I avoid because of the lack of experimental design and results detail I am looking for. For our activity, we found our article on the Public Library of Science.

 

2. Filter for articles with simple graphs. Summarize those articles.

After I find an interesting research, I look for one thing: simple graphs and tables for students to analyze. Do the results of the article have bar graphs, line graphs, or regression curves? If so, then I tend to use the article. Does the research include data tables with easily understandable variables and measurements? If so, I tend to use those too.

 

3. Create questions with a focus on science skills.

For me, the most simple questions to come up with focus on data analysis and experimental design. For example…

• What is the independent variable and dependent variable in this experiment?
• By looking at a graph, what is the value of y if given a value of x? Or, what is the value of x given a value of y?
• What possible change could we see in the graph if we changed another variable?
• How can we increase/decrease a certain x or y value on the graph?

There are no limits to the way we ask questions. But, to make things easier, I try to stay focused on measuring the science skills I value.

 

Field notes

• I like to use online bubble sheet programs (like Zipgrade). Besides being a quick and easy method to marking multiple choice questions, most of these programs including Zipgrade are able to track which which choices students selected for each question and also tally what percentage of students got certain questions right or wrong. This way, I get to know which questions and concepts were particularly challenging for the class so I can address those issues. I also potentially get to know which roadblocks an individual student is encountering by referring to the answers they selected.

 

Wrap up

Long after a student forgets the content we teach them (ie. the names of each stage of mitosis, Bohr and Lewis diagrams, evidence for continental drift), we hope students remember how to problem solve and think like a scientist. If science skills are what we value as educators, and I do, then I need to find a way to measure it and for students to practice it. Although a multiple choice assignment/quiz may have some drawbacks, I believe it’s quicker than reading lab reports when trying to assess a student’s science competencies.

If you want more of our samples, our REAL Science Challenge contests also have similar questions and passages. And, we also host the REAL Science Challenge contest series which feature passages and questions that measure and practice science skills and is written by students from around the world.

To download our sample quiz, click the link below.

 

Until next time, keep it REAL.

 

Resources

Handout(s): 14 – Science Skills Quiz

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Team building is an important part of running a class. And, it requires constant upkeep. If I want my car to run smoothly throughout the year, I can’t change the oil once a year and expect it to last. Similarly, I can’t just do a science team building activity at the beginning of the year in class and expect that classroom spirit to continue throughout the year. Classroom culture needs to be continuously supported by regular team building.

 

Unfortunately, team building activities are often difficult to do. This is mainly due to curricular constraints. That is, there’s simply no time to do team building because the curriculum comes first. Or, teachers need to justify how the team building activity they’re doing links to the science curriculum. In our science team building activities, we overcome these hurdles by having students solve a physical science problem creatively. We also place an element of friendly competition along with it. Below is one science team building activity I’ve used for the past few years, and kids have always enjoyed it. Handouts are available at the end of this post.

 

Using Past “Technology” to Teach

The activity I use as a science team building activity is basically a mashup of the children’s games “Telephone” and “Charades”. The activity is kind of like semaphore – where seamen use flag patterns to send messages between naval ships. Similarly, in our activity, a message is sent from one person to another using body actions – no talking is allowed. And, students cannot run towards each other either (or use a mobile device). I first did this activity back in 1996, when I was in high school myself, at a science competition. I didn’t know it back then, but the activity taught computational (ie. coding principles), critical, and creative thinking. The activity also forced me to work closely with my team members. Twenty-one years later, I use this activity typically between grading terms or units – to give students a bit of a mental break.

 

The goal of this activity is to send a message (a randomly generated pattern of 16 X’s on a 8×8 grid) to another person holding a blank 8×8 grid. Since the person holding the original message (ie. the sender) is must not yell or physically pass the message to the person holding the blank grid (ie. the receiver), the sender must use body gestures to pass the message to the receiver. The sender and receiver must work together beforehand to determine a “code” they will use to send and translate the message.

 

For example, one code could have the sender read the grid from left to right, one box and one row at a time, and indicate an X by putting a right hand up and the absence of an X by putting a right hand to the right hand up. The receiver would watch the sender and starting place an X in the box or leave the box blank, going left to right, one box and one row at the time. That’s one sample code, but is it the fastest? In order to win the science team building activity, the winning team must send and receive the message in the shortest amount of time.

 

One more twist

The sender and receiver must send the message around a corner (ie. around the corner of a hallway or a building). Sender and receiver cannot see each other. For example, if the sender is standing at the southwest corner of the building, then the receiver should be standing at the northeast corner.

 

So, how can the message from the sender get to the receiver if they cannot see each other? Well, there’s a 3rd person on the team – a middleman. In the above example, there would be a middleman standing at the northwest corner of the building. The role of the middleman is to relay the message between sender and receiver. The middleman watches the sender and copies the sender’s exact actions, while the receiver watches the middleman and translates the message. This is where the “Telephone” aspect of the activity comes into play.

 

Field Notes

• Each team has 3 members.
• Give teams 1 day to prepare. One day is more than enough time to come up with and practice a code.
• Make it clear to students that they will receive a randomly generated pattern of X’s on a 8×8 grid on competition day. It is randomly-generated. One year, I had a group of students practice a sample message for only 15 minutes. Then, they sat down for the rest of the class. They said they were finished. At the end of the class, I told them they would get a different message to send next day. They were surprised!
• Each error adds 15 seconds to team’s final time.

 

Putting it all together

Science team building activities are great not just to build or maintain an awesome classroom culture but also to give students a break sometimes. Giving students an active, open ended challenge with an element of friendly competition does the trick for me. And, the fact that these challenges tie in aspects of the curriculum (ie. building and prototyping, working with others, solving problems using critical and creative thinking) make them easier to justify. If you want the notes and illustrations to how I set up our REAL Science Semaphore Coding challenge, click the link below and download the handout.

 

Until next time, keep it REAL.

 

Resources

Handout(s): 11 – Sample Challenge – Semaphore

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Is there something we can do to start teaching STEM in a simple way? STEM (Science, Technology, Engineering, and Math) is an increasingly popular way to teach science and math in a holistic, applied way by using the engineering design process. Teaching stem gives off the impression that it requires teachers to go well beyond their comfort zone. Thus, it appears to be a huge mountain to climb. Teachers may feel the pressure to create all new lessons, to learn computer programming, and to start making robots in their spare time. That’s not necessary at all.

 

We believe teaching STEM can be done by making some changes to your current teaching practice. In this blog, we demonstrate how we take a traditional cookie-cutter lab and extend it to include elements of STEM. At the end of the post, you can download our lab and the extension activities. We give you our peanut lab and So how? The peanut lab and making an effective calorimeter.

 

Extend beyond the lab

One approach to start teaching STEM is by extending current labs to include elements of STEM. In this case, we propose having students design and build systems that increase the efficiency or accuracy of a lab. We are not suggesting students build a better thermometer or a better metre stick (although, that would be a pretty cool STEM lab too). Rather, we are suggesting that if temperature (ie. heat transfer) is what students are measuring, then perhaps students can also design and build a system that prevents heat loss. If students are measuring the height of a building (ie. distance), then perhaps students can design a way in which students can measure the height more effectively than just using metre sticks, measuring tape, or relative distances.

 

What’s old is new again

Every year, my students do a lab where they burn peanuts to determine how many calories of energy per gram is in a peanut. This is not a new lab. I did a similar lab when I was a young lad back in the 80s.. And, I found a similar lab in a science textbook published back in the 90s, which I used as inspiration for the lab my students do. In our lab, students put a peanut on top of a peanut stand (which they make using a paperclip) and light it on fire. The fire heats up a small beaker of water that is suspended above the beaker. Students use the change in temperature of the water to calculate the amount of heat energy absorbed by the water which, in an ideal system, would equal to the amount of heat energy released by the peanut.

 

Unfortunately, the experiment is not run under ideal conditions. There are many ways in which the heat from the peanut can escape and not reach the beaker. Furthermore, there is heat loss from the inefficient transfer of heat between the beaker and the water. When students run the lab the first time, they use tin foil to create a chimney around the peanut to prevent heat loss. However, when students compare their results to the published number of calories per gram found in peanuts (thanks Google!), the student results still come up short.

 

Thus, we challenge students to build a system that prevents heat loss and improves their results. The challenge works in so many ways. It is open-ended. It requires students to collaborate with each other and do research beyond their own classroom learning. And, it results in students asking some interesting questions (ex. How can I produce a fully closed system? How will I light the peanut and ensure oxygen flow if the system were completely closed? What can I use to hold the water?). Most importantly, it requires students to build and test, which, I believe, is a big part of teaching STEM.

 

Field Notes

• due to peanut allergies, we sometimes use potato chips too. They burn very well due to their oily nature.
• do not use marshmallows or gummy bears. They may appear fun and interesting, but the result is a messy goo that doesn’t burn very well
• keep the food labels for the food you burn. The students will use the Calorie information on these food labels to compare with their own experimental results.

 

Putting it All Together

I don’t believe teaching STEM requires a herculean change in our teaching practice. We can teach elements of STEM in our labs by focusing on the efficiency and results of the lab. Currently, we may ask students “What would you do next time to improve the results of your lab?” but not offer any follow through. Well, by teaching STEM by actually building systems that improve efficiencies, your students now can put their ideas into action. If you would like a copy of our peanut lab, please click the link below.

 

Until next time, keep it REAL.

 

Resources

Handout(s): 08 – Peanut Burning Lab Handout

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Students are always looking for a “right answer” in science, which leads students to be myopic when it comes to analyzing data. “What am I supposed to get” or “What is supposed to happen?” are common lines I hear from students as a result of the quest for a right answer. In labs, the expectation of a right answer results in students expecting that there needs to be an effect in an experiment. An experiment should always result in an increase or decrease in something, right? And when that doesn’t happen, there must be something wrong with the experiment or data, right? That’s not the right way to approach a lab when analyzing data.

 

The Big Idea

Students need to realize that no effect/answer is sometimes a right answer too. In the late 19th century, scientists believed that space was filled with a so-called “ether” that allowed light to travel between the sun and the earth. Albert A. Michaelson and Edward W. Morley devised a method to measure the effect of the ether on the speed of light. However, when they were analyzing data, they were not able to detect the ether, scientists realized there was no ether at all. That was an amazing discovery – a result of a lab that produced no effect. This is known as a null hypothesis. We teach students all about writing hypotheses and testing hypotheses, but rarely do we ever talk about identifying a null hypothesis. So, how can we have students practice this useful science skill?

To have students practice identifying null hypotheses, we give students a lab where there is a null effect. It’s even better if the null effect conflicts with what students believe (because students will already be looking for a specific result). We use a pendulum lab to illustrate null hypotheses. And, at the end of the post, you can download our handouts.

 

Life sized example of null hypothesis

The inspiration for our lab comes from a fantastic video of former MIT professor Walter Lewin’s last lecture (where he features his “best of” segments). In it, he swings on a massive pendulum (circa Miley Cyrus’ Cannonball video) to make a point about uncertainty and error. That is, the mass at the end of a pendulum has no effect on the period of a pendulum’s swing. To check out the video, click video clip below (demo starts at 10 minutes in)

 

 

In our 1st version of this lab, students create a pendulum (using a ring stand, ring clamp, and string) and hang different masses from the end (starting from 50, 100, 150, 200, and 250g weights). Students start swinging their pendulums from the same height and measure the time it takes to complete 10 periods (ie. cycles). Then, they divide the time by 10 to get the time for 1 period. This version uses items that are already present in most labs. But, a problem that arises is that larger masses can affect the length of the entire pendulum. The length of the pendulum is from the point of rotation to the bottom of the weight. Since 250g weights are longer than 50g weights, the pendulum using a 250g weight is also a longer pendulum. We want to control for length in this lab (because the length of a pendulum does affect period)..

 

Thus, in our most recent version of this lab, students tie washers at the end of the pendulum instead of using weights (this idea came from a similar lab we saw on Stanford’s website). Students start by tying 1 washer at the end of the pendulum and then adding 1 more for each trial until a maximum of 5 washers. This version requires less mass. And, we can keep the length of the pendulum at a consistent length too (which makes analyzing data easier). By making sure the washers are tied together and that the length between the tops of the washers and the point of rotation is kept consistent, the lengths of the pendulum for all 5 trials are kept consistent.

 

Field notes

• Pendulums need to be swung no more than 10 degrees away from rest position. Have students use a protractor to make sure they are not swinging from a greater angle.
• Find washers that are the same size. This way, the increases in mass are the same each time a student adds a washer.
• Have students leave plenty of slack at the end of the pendulum. Students will use the slack to add washers while keeping the length between the washers and pivot constant.
• Remind students that they will find the time of 1 period of rotation by taking their time for 10 periods and dividing by 10. Many students forget and end up measuring one period.
• A lot of students will ask if it is correct that their results fluctuate with no apparent trend. I usually say tell them to run the trial again carefully. If they already have, then I say, “well, those are results then.”
• There is no effect of mass on period. Only length of pendulum and acceleration due to gravity have an effect. But, don’t tell students that.

 

Putting it all together

A null hypothesis is an underrated yet important part of doing science. Students need to be able to identify it when it happens instead of always expecting a result or trend during an experiment. Ultimately, we want students that are not only good at doing an experiment but also good at analyzing data and concluding what their results mean. And, sometimes, their result may indicate nothing happened. And, that’s fine. That still puts students one step further of where they started. If you want a copy of our lab handouts, click on the link below.

 

Until next time, keep it REAL.

 

Resources

Handout(s): 06 – Pendulum Lab Handout

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A periodic table lesson can be boring because it focuses on facts. We should focus on the application – it’s much more exciting! So, what’s the most amazing application with regards to the periodic table? It’s that it allowed Mendeleev (who first proposed a version of the periodic table that led to development of the modern periodic table) to predict unknown, yet-to-be discovered elements. It was a powerful tool that helped scientists discover new elements (like Germanium). So, how do we teach students to recognize how amazing this aspect of the periodic table is?

 

Unfortunately, most worksheets and videos used in a periodic table lesson tend to focus on the facts and structure of the periodic table (arranged by increasing atomic number and grouped by similar properties). Projects that require students to research an element aren’t much better. Students can simply regurgitate what Wikipedia tells them. My question when it comes to worksheets, videos, and projects is in the application, namely, where’s the application in all that information? Where’s the excitement that comes from “doing” science and not just learning about science?

 

Have Students Use What They Already Know

Today, in my first periodic table lesson, I have students develop their own periodic table. Not of known elements. Instead, students make a periodic table of chocolate. Then, they use their crude periodic tables to discover “new” chocolate combinations. It’s a tribute to what early scientists like Mendeleev were tasked with (ie. create an order to known elements) and allows them to apply their tables in the way Mendeleev did. Near the end of this post, you can enter your email to receive a free copy of my instructions and templates (which includes 24 cut outs of chocolate bars and their descriptions) to this activity.

 

Our Set Up and Notes from the Field

Our activity is simple in its objective and open ended in its execution. Given a set of 24 different chocolate bars (ex. Kit Kat, Toblerone, Caramilk, Aero), students work in small groups to create a single periodic table that must group chocolate bars with similar properties on both horizontal rows and vertical columns. They must also indicate what properties they used to group similar chocolates in specific rows and columns. Refer to sample periodic table of chocolate using 8 chocolate bars as an example of what’s supposed to happen.

The activity is simple because most students at least know the characteristics of each chocolate bar (if not, a description on the templates have been provided). Thus, grouping like chocolate bars together is not difficult for students. And, surprisingly, I’ve never seen two periodic tables to ever be alike because every student uses different characteristics to group and organize their tables. This is where the activity is open ended.

 

When students are finished organizing their chocolate bars onto their periodic tables, they look to the blanks in their tables. Such blanks can be used to predict new chocolate bar combinations by looking at the groups they are organized alongside (similar to Mendeleev discovering new elements by looking at elements with similar characteristics found in the same group).

 

Extra Tips

Here are some tips if you plan on running the Periodic Table of Chocolate activity with your class:

•  encourage students to be creative when it comes to grouping together chocolate bars. This will help classify outliers and bring more critical thinking into their table. For example, we can group Dairy Milk and Aero Bars together because both are pure milk chocolate. But, we can also group them together because they are “breakable” bars (and so are Kit Kats and Toblerones).
• encourage students to leave blanks if they feel no chocolate bar in the set fits the space provided. The 24 bars do not need to make a perfect shape (ie. rectangle or square) with no blanks. Not all the chocolate bars will group perfectly. And, that’s fine. Blanks are opportunities for students to create their own bars.
• there is no size limit to the periodic tables. The only limit is student’s ideas for grouping.

 

Putting it All Together

The Periodic Table is not just a chart that hangs in a science classroom but an amazing tool as well. Remember, a periodic table lesson doesn’t need to be boring. We just need to teach how amazing its development was. By applying its principles to the simple task of organizing and predicting chocolate bars, we can recreate just how Mendeleev must have felt when he was trying to organize his elements at the time. Click the link below to grab the handouts.

 

Until next time, keep it REAL.

 

Resources

Handout(s): 03 – Periodic Table of Chocolate Instructions | 03 – Periodic Table of Chocolate Templates

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