Writing Rules

Est. Class Sessions: 1–2

Developing the Lesson

Part 2. Using Different Units

Show students the collection of objects you gathered before the lesson. Show students a quart and a cup.

Ask:

Using your answer to Question 3 in the Student Guide, how many cups are in a 1-quart container? (4 cups)
How many cups are in a 2-quart container?
(8 cups)

Tell students that these reference units will be available as they explore the relationships between other units of measure. Assign Questions 1–6 on the Using Different Units pages in the Student Activity Book. Working in pairs, students find the missing values in function tables.

For some tables, students write the rule. Encourage them to use a guess-and-test strategy to test their rule.

For some tables, the rule is given, and students are asked to check if it works and to describe the rule in words. Students are also asked to use rules and patterns to solve problems.

After student pairs have had a chance to work through Questions 1–6, ask them to share their rules and explanations. In Question 2C, students are asked to choose the smallest bottle of juice for a recipe that needs 10 cups.

Ask:

If Lee Yah can purchase more than one bottle of juice, is there another option? Explain. (Buying the 96-ounce bottle leaves a lot of extra juice. However, since Lee Yah needs 80 fluid ounces of juice, there is not another option. If she were to purchase a 64-ounce bottle and a 12-ounce bottle she would be 4 ounces short. If she purchased a 64-ounce bottle and a 32-ounce bottle she would still have 96-ounces of juice.)

In Question 3, students should notice that the input and output are the same. Therefore, the rule is: Volume in Milliliters is equal to the Volume in Cubic Centimeters.

In Questions 4 and 5, students are asked to test and check rules shared by students from Mrs. Dewey's class. Ask students to explain why some rules do not work.

Testing Rules. Testing possible rules is a way to improve students' abilities to identify the patterns and the rule relating the input and output. Ask students to think about all the ways to get from an input to an output and then test each possible way. A rule must work for all input numbers. Some students will have trouble identifying rules to test, but will eagerly test possible rules. This testing will develop students' abilities to find, identify, and extend patterns in a data set.

Student Guide:

Student Activity Book: 553 554 555 556

Answers