M & M Probability Lab

When learning about probabilities in middle school genetics lessons, you will find that many students still struggle with basic math skills, especially if you teach an on level or resource class. This is one reason you may want to add a lesson that reinforces math concepts such as percents, tally marking, decimals, fractions, ration, and probabilities. These are all basic math skills that students should have learned by the time they are solving Punnett Square word problems, but many may still struggle with. The more students are exposed to math in other content areas, the better for them.

The Probabilities with M & M's Activity is one that can be definitely used in a math class, but also in a life science class. In middle school life science, it will cover the concepts of experimental probability and theoretical probability, which helps students understand the role of probabilities in how organisms get their genotypes and phenotypes at a random chance.

In the M & M lab, both theoretical and experimental probability are explored. Theoretical probability is the likelihood that an event will happen based on math or reasoning. It does not involve any type of experiment. It is calculated by taking the number of favorable outcomes and dividing that by the total number possible outcomes. For example, the odds of flipping tails on a dime theoretically are 1 out of 2, or 1/2, or 50% likelihood.

Experimental probability is the likelihood that an event will happen based on experimentation. Unlike theoretical probability, it relies on doing trials or experiments. In this lab, students will conduct several trials where they randomly select M & M's and record which color they get each time. Students should find that the more trials they do, the closer the experimental probability will be to the theoretical probability.

*To do this lab, make sure to tell students to bring in a regular size bag of M & M's, not

the tiny fun size bags.

One regular sized M & M bag per student

Materials:

1. Regular sized bag of M & M's

2. Science notebook for recording data

3. Paper towels

4. Small condiment sized containers (optional)

5. Calculators (optional)

For the Theoretical Probability:

1. Takeout all the M & M's and place them on a paper towel.

2. Count all the M & M's that were in the bag and record the total in your science notebook. Create a table for this before you begin.

3. Separate the M & M's by color as in the picture below. You can place them in piles on the paper towel or place them in their own condiment container.

4. Count the number the M & M's in each pile.

5. Record the number of each color of M & M's in your data table.

6. Get the ratio for each M & M color. For example, if you got 10 reds out of 52 total M & M's, you would get a ratio of 10/52.

7. Using a chart, write this ratio as a decimal, fraction, and a percent.

   
   

*You may want to remind students that more likely something is, the closer to one the probability will be, so .80 is more likely a chance than .40.

This is one bag of M & M's sorted by colors and placed in small containers.

For the Experimental Probability:

1. Randomly pick an M &M from the bag 50 times. In your science notebook, make a table to record your results for each color M & M. Write a tally mark for each M & M picked.

2. Once you complete the 50 trials, you will calculate the experimental probability for each color M & M.

3. You will convert the fractions to decimals and percents using a data chart. To change a fraction to a decimal, divide the numerator by the denominator. So, assume we have 25 blue M & M's out of 50 total M & M's, this is 25/50. If you divide this fraction, you get .5.

4. Then change the decimal to a percent, move the decimal two places to the right, which will make the decimal number of .5, 50%.

   
   

Students can answer these questions in their science notebooks:

1. What is probability?

2. What is the difference between theoretical probability and experimental probability?

3. Did your experimental probability for blue M & M's match the theoretical probability for blue M & M's?

4. In the bag of M & M's, which color was there the most of? Least of?

5. Which color did you pick the LEAST often when choosing a color randomly? What was the probability (look at your data chart)? Did you expect this probability knowing the theoretical probability for this color?

6. What role does probability play in genetics?

At the end of the lab, students should be able to know the difference between theoretical and experimental probability and better understand the likelihood of an event occurring in the real-world setting.

*If you like the condiment containers with lids in the picture, I highly recommend these. If not for this lesson, you can use them for a "Fun Fridays" idea in your class. Place different amounts of candy in each one. Say one has 12 gummy bears in it, another has 10 M & M's, another maybe three gummy worms, another maybe five mints, another one Hershey Kiss. You can make one have 1 M & M in it as a joke :). After discussing probabilities, have them figure out the likelihood of choosing the less desirable container (The one with one M & M in it). Keep the lids on them so students do not know what is in each one. If students have been behaving well, you can reward them with this kind of fun activity to end the week.

How to select a student to come up to pick: I like having popsicle sticks in a cup, each one with a different student's name. This is something to set up the first week of school. Choose a popsicle stick at random, by closing your eyes and drawing one. Read the name that was picked to the class. Tell this lucky student to pick a container. Open it to see what they won. You can choose a few more names. If you don't want to give out candy in class, you can think of other fun tangible rewards to put in them, like maybe small erasers, or 3D printed toy animals- I find many students love small 3D printed figures.

But if nothing else, I use my condiment containers for salad dressing I put in my lunch container, or to store nuts in that I bring to work to snack on (portion controlled). It is also great for storing left over sauces, garlic, and other tiny leftovers. They're cute, compact, and come with a tight seal.