# Teaching rate through recipes

### Adapted: http://illuminations.nctm.org/Lesson.aspx?id=2854

## Common Core Standard

CCSS.Math.Content.7.RP.A.3

Use proportional relationships to solve multistep ratio and percent problems. Examples: simple interest, tax, markups and markdowns, gratuities and commissions, fees, percent increase and decrease, percent error.

## Before

I will start the lesson by asking students if they have ever cooked before. If they have, do they cook with a recipe? I will let a few students share some things they have cooked and the ingredients they add into making the food. I will then share one of my favorite macaroni and cheese recipes and write it on the board. Then, I will ask students if they have ever had to double a recipe, triple or even half it for smaller amounts. I will share with the students that I once had to make enough macaroni and cheese to feed 100 people. I will ask students how they think I changed my recipe that once made enough for ten people to now make enough for 100. Students may bring up adding, multiplying or even ratios. I will then ask students a few questions about what they notice about the recipe. If they don’t come to the conclusion I will show them that a lot of the measurements are in fractions like ¾ a cup milk and ½ teaspoon salt.

I will then hand out the activity sheet to students. “After handing out the activity sheet to the students I will explain to students that they will be looking at a recipe for chocolate chip cookies, and modifying it to feed different numbers of people. They will be calculating how to prepare 12 cookies for a family meal, 60 cookies for a party, 24 cookies for a class event, and 300 cookies for a bake sale. They need to determine how much of each ingredient they will need.”

I will let students know they need to put their final answer in fractions because that’s how most recipe measurements are written.

I will then go over the common measurements of tsp= teaspoon, c= cup, ect.

I will have premeasured amounts of the ingredients in separate bags up in the front of the room so students can see what 36 servings of each ingredient looks like.

I will also provide students with a table of the ingredients and measuring cups where if needed they can measure out their ingredients to check how it compares to the initial amount.

## During

I will walk around and see how students are completing the activity sheet. After a few minutes of the students working I will ask some students to share the strategy they used for finding flour in the different serving sizes. I will write the strategies on the board. Listing some strategies may help students who were stuck get started. The students will then continue working on their own and I will walk around the room answer questions.

Questions

What strategy are you using to complete the activity?

How are you using the ratio to help you answer the problem?

Are you consistently using the same strategy?

Is it possible to buy a fraction of an egg or a bag of chocolate chips? What should you do when that occurs?

## After

**After**

I will bring the class together to talk about the different strategies being used. I will ask the students who used a ratio or proportion to solve for the serving sizes of salt. I will then go over the answers with the class.

I will ask the students:

- in what other ways can they use ratios or proportions to solve similar problems

- Would it have been easier to calculate using decimals? Why do you think cooking instructions are made it fractions?

Write down in their journal how confident they felt using their strategy and if they would like to try a different strategy in the future. Turn in worksheet

## Gearing Up

- Have students come up with their own recipe and exchange with a neighbor for it to now make 12 servings.

-Have students convert the units to the simplest form of measurement. For example for 3 and 1/3

tsp it would be easier to measure 1 tbsp + 1/3 tsp. I would provide that 1 tbsp = 3 tsp and other measurement equivalences.

- Do it backwards question: If there are 17 eggs used for 300 servings of cookies how many eggs are in the single serving of 36 cookies?

## Gearing Down

- Have measure cups and spoons for the students to visualize what the measurements look like.

- Provide cut out illustrations of the ingredients for students to use as manipulatives

-Have vocabulary measurement printed handouts for students example tsp= teaspoon

-Pre fill a few measurements out on the chart

-Encourage students to use the measuring station to compare the likely hood of their results with the initial serving amount.

## Mini Activity

Trade with a partner group and change the recipe to make enough food for 60 servings? 6?