Using food to introduce variable expressions

Are your students food motivated? How long does it take them to notice if you have a bag of candy in the room? Mine can sniff it out like bears! Let’s capitalize on that motivation by using fun-sized bags to create and substitute into variable expressions.

What’s in the bag?

Any single-serving bag with a variety of items will work for this activity. You can use the colored goldfish cracker snack packs, fun-sized bags of M&Ms or Skittles, Chex-Mix, trail mix, fruit snacks, etc. Or get a big bag of one of the items and a measuring cup to dole out the same amount for each student. Let the students sort their serving into color or type of item. Then, as a group, assign variables to each item. If you anticipate that your students will have trouble assigning variables to each item, OR that assigning variables will become a behavior management issue, you can put all of the letters in the alphabet into a bag and draw the letters to match with the items.

Assigning variables

For example, if you are using M&Ms, you will need to establish a variable for each of the colors. You may decide on:

• Brown = b
• Yellow = y
• Red = r
• Orange = o
• Green = g
• Blue = x

But it is important to note that students can use any variable to represent a color. It does not have to be the first letter of the color. And, in this case, it cannot be the first letter of the color for both brown and blue because having two of the variable b will make it too difficult to distinguish between the two colors when writing expressions.

Ok, so we have them sorted and we have assigned variables, now what?

Creating expressions using food

Now we start creating expressions. Ask your students to write an expression to represent the M&M color they have occurring the most in their serving. Now ask them to write an expression to represent the M&M color occurring the least in their serving. They have just written two one variable expressions!

Two variable expressions

Move on to two variables…Ask your students to choose the two colors they like the most and write an expression representing how many of those two colors they have altogether. Ask your students to choose the two colors they like the least and write an expression representing how many of those two colors they have altogether. They have just written two more expressions with two variables each!

Now, create two combinations of three colors each and ask them to write the expressions to represent each of those color combinations.

Great! We have expressions, but what do we substitute in for each variable?

Substituting for each variable

You have a lot of flexibility here. Do you want your students to be working with only positive numbers? How about monetary values? Do you want them to practice working with integers? Or do you want your students to substitute in variable terms? The options are endless! Here are a few examples.

Positive Numbers ONLY

• b = 1
• y = 2
• r = 3
• o = 4
• g = 5
• x = 6

Money

• b = $0.02
• y = $0.05
• r = $0.10
• o = $0.01
• g = $0.25
• x = $0.07

Integers

• b = – 1
• y = 2
• r = -3
• o = 0
• g = 5
• x = 4

Integers and Variable Terms

• b = 3t
• y = 2
• r = -d
• o = -4
• g = 5d
• x = -2t

AND, the best part about the whole activity is that it is edible! YUM! Keep their brains active, tummies full, and the lessons engaging. Most of all, have fun! Click here for the printable version.

Do you want even more activities for working with students on variables, terms, and expressions? Click here for guided notes and interactive notebook activities.