## Water Bucket Relay

### Cindy Jacobs

#### Description

This lesson includes subtraction with more than one renaming.

#### Objectives

The student explains and demonstrates the addition and subtraction of whole numbers (up to three digits or more) using concrete materials, drawings, symbols, and algorithms.

The student solves real-world problems involving addition, subtraction, multiplication, and division of whole numbers using an appropriate method (for example, mental math, paper and pencil, concrete materials, calculator).

#### Materials

-Chalk
-Construction Paper (cut into water bucket shapes)
-Markers

#### Preparations

1.Cut out enough water buckets shapes from construction paper for each student to have one. Write a different three digit number on each one. These numbers should be less than the smallest number written inside the sections of the ladder (rectangles). For example, if the smallest number used is 315, then all the numbers on the water buckets should be less than 315. The digit in both the tens and ones place needs to be greater than the number 5.
2. Draw a large fireman's ladder on the chalkboard using the directions listed in the procedures.

#### Procedures

1. Write several three digit subtraction problems on the chalkboard. These problems should require more than one renaming. Use a vertical format. Explain to students that sometimes you have to rename to show more ones or tens in order to be able to subtract. Tell students to always subtract from the top down not the bottom up. A common problem is that some students will try to subtract the minuend from the subtrahend. Work these examples.

2. Next, draw the perimeter of a large rectangle on the chalkboard (lengthwise across). Divide this giant rectangle into twelve smaller rectangles with the perimeter as the outer boundary. It should resemble a fireman's ladder. Draw a fire on one of the end rectangles and label it. Write the words Fire Station on the opposite end rectangle. You can even draw a building to symbolize a Fire Station. Label each of the rectangles in between with one of the following numbers: 643, 831, 522, 711, 334, 412, 754, 315, 844, 546. Use only one number for each rectangle.

3. Tell the class we're going to play a subtraction game called -Water Bucket Relay-. Divide the class into two teams. Decide which team will go first.

4. The first player on the team carries the water bucket from the beginning (Fire Station) to the first section of the ladder. The player subtracts the number on the water bucket from the number in the first section of the ladder. If the answer is correct, the next player carries the bucket into the next section of the ladder. This continues until a player -Spills the Bucket- (gives a wrong answer) or puts out the fire (reaches the Fire) by answering every problem correctly.

5. When a team -Spills the Bucket- (gives an incorrect answer) or reaches the fire, the player from the opposite team starts where the other team left off (or the Fire Station) and proceeds toward the fire. Each time a bucket is spilled or the fire is put out, the number on the water bucket is replaced with a new water bucket and number.

6. Five points are given each time a team puts out a fire. At the end of the time period, the team with the highest score will be deemed the winners.

7. When through playing the game, give each student a sheet of paper.

8. Pass out one water bucket to each student. Each student will create 10 three digit subtraction problems using the 10 numbers from the ladder and subtracting the number written on the water bucket. Before they begin, have students explain when and why they may have to rename when using subtraction.

9. Allow students time to work the ten problems. Collect the papers for assessment to evaluate the effectiveness of this lesson.

#### Assessments

1. Mastery or non mastery will be based on student observation. While students play the game, see whether or not they understand the concept of renaming more than once.
2. Each student should get 8 out of 10 subtraction problems correct on his/her paper for mastery.

#### Extensions

This game can be used with various addition, subtraction, multiplication, and division problems to accommodate your objectives.