Demonstrating fractions and ratios with pizza slices circumvents students’ math fears
By Adam Weiner, CFSE
“There is nothing new under the sun.” Ecclesiastes
“There’s fractions in my subtractions.” Jimmy Buffett
A few years ago I started using pizzas to teach fractions, percentages and ratios.
In discussing this article with my daughter, an outdoor education instructor who is currently working on her California Teaching Credential, she told me she has used this technique for years and that other teachers have done so as well. So, if you already use pizzas for teaching math, I suggest you take a look at the index of my first 75 articles and find something new to you. If you have not used pizzas to teach culinary math, then keep reading. (Although, feel free to look at the index as well.)
It is far from new that our students seem to know less and less math each year. Nearly six years ago, I published an article on assessing culinary math skills. It has already received nearly 4,500 hits, which shows me culinary teachers at all levels are still having difficulty with students’ lack of math skills. One of the biggest problems we all face is when we even say the word “math” our students freak out, tune out, or both. The trick becomes how we can teach math in a way that they don’t realize they are learning math.
I use pizzas. Every student knows what a whole pizza looks like. Every student knows what a half of a pizza looks like from ordering different toppings. Combine two halves and you get a whole. Or, said another way, one-half plus one-half equals one. (Note: I know this sounds incredibly basic, but more often than I can remember students have come up to me and asked for a two-fourths measuring cup. When I say that is the same as a one-half measuring cup they tell me I am wrong and explain, “I added one-half plus one-half and that equals two-fourths.”)
I recommend presenting two pizzas for your culinary math teaching. One pizza cut into four pieces and one pizza into 10 pieces.
The Four Slice Pizza: Twenty-five percent increments are very standard in the kitchen when measuring solids and liquids. Students need to understand one-fourth ratios, for example four quarts make up a gallon and four butter cubes make a pound. Students also need to know the reverse: one pound of ground beef yields four quarter-pound burgers. Thirty-two ounces of milk yields four eight-ounce servings. Furthermore, many recipes of all types—sweet, savory, baking, etc.—are based on quarters. Thumb through your recipe collection and you will see this repeatedly. With your four slice pizza you can easily show a quarter, half, three-quarters and 1 and add, subtract, multiply and divide at will. (Don’t forget to use this pizza to show: a quarter plus a quarter is a half; a quarter plus a half is three-quarters; and a quarter plus a quarter plus a quarter is three-quarters.) This pizza is also good for teaching percentages of 25 percent, 50 percent, 75 percent and 100 percent as well as ratios of 1:1, 2:1, 3:1 and 4:1.
The Ten Slice Pizza: I won’t bring up teaching the metric system because that even makes many culinary teachers freak out, tune out, or worse do both. (For those of you who are reluctant to try the metric system, let me just give a single teaser as to its advantage: no fractions.) A 10-slice pizza is great for teaching fractions of one-tenth, one-fifth, three-tenths, two-fifths, one-half, three-fifths, seven-tenths, four-fifths, nine-tenths and 1.
Use this pizza to show as many combinations as possible such as three-fifths plus one-fifth is four-fifths but so is two-fifths plus two-fifths. Demonstrate that nine-tenths minus two-fifths is one half, etc. It is also very useful for teaching percentages of 10 percent, 20 percent, etc. up to 100 percent. Ratios of 10:1, 2:1, 5:1, etc. are easily taught with this type of pizza.
The leap from percentages to ratios is a small one. I put 10 slices of pepperoni on a pizza and tell the students that is half the amount and have them bring it up to the full allotment.
The beauty of working with pizzas, cookies, cupcakes, etc. goes beyond turning off the student at the mention of the word “math.” You have the advantage of students wanting to show up for class when they learn they will eat their classwork. A caveat though: Don’t tell them ahead of time you will be teaching math!
A closing note: I am leading a round table discussion at the CAFÉ Leadership Conference in June on ways to spark your students’ interest to learn. Pizza math, flipping fish, clarinet playing and other unique and crazy ideas will be discussed. Come join me if you can and tell me your creative ideas so I can write about them and bring them back to my own class.
Chef Adam Weiner, CFSE, teaches a 20-week Introduction to Cooking program for JobTrain on the San Francisco Peninsula, and is a frequent presenter at CAFÉ events throughout the nation. He is also a recipient of the prestigious Antonin Carême Medal.