## Baby Weight

• Lesson
Pre-K-2
1

In this lesson, students work with data to complete an organized chart by doubling or halving numbers, and they compare data using vertical and horizontal bar graphs.

Begin a class discussion about what it means to double or halve numbers. Ask students to give some examples of doubling or halving (e.g. half of 4 is 2; double 10 is 20; and so on). Ask students to share some situations in which they would double or halve numbers (e.g. baking, making groups, etc.).

Bring a group of students up to the front of the room, such as 5 students, and ask them how they would double the size of the group. Each student can pick another student to join the group at the front of the room.

Next, bring a group of an even number of students to the front of the room. Tell them to halve the group. Send half of the group back to their seats.

Distribute the Baby Weight activity sheet to each student.

 Baby Weight Activity Sheet

Discuss the "rule of thumb" as stated on the activity sheet: A baby doubles its weight in six months. Complete the first two rows as a class. Give students time to complete the rest of the chart individually.

Using a red crayon for the birth weights and a brown crayon for the six-month weights, explain how to complete the bar graph. Students should pair up and compare their bar graphs. The teacher can circulate throughout the room to check for accuracy.

You may wish to have students create additional bar graphs for other babies, similar to the ones in questions 2 and 3 on the activity sheet using grid paper.

 Grid Paper

Solutions to the Baby Weight Activity Sheet

The following are the missing numbers from the chart (question 1):

Amy 10
Benito 8
Cathy 18
Demetrius 16
Erik 14
Fran 6
Greg 5

As a class, discuss the similarities and differences between the two graphs completed (questions 2 and 3 on the activity sheet.) Students may point out that both graphs are bar graphs and show a comparison between birth weight and six-month weight. Students may also say that the graphs show the weights of different babies and the fact that they "look" different (one is horizontal and one is vertical.

References

• Parker, Tom. Rules of Thumb. 2 vols. Boston: Houghton Mifflin Co., 1983, 1987.
• Cook, Marcy. "IDEAS: Applications." The Arithmetic Teacher. Vol. 36, No. 8, April 1989, pp. 27-32.

Extensions

1. Students can order the students' weight at birth from least to greatest. [Solution: Amy, Fran, Erik, Benito and Demetrius tied, Cathy, Greg]
2. Students can find out (from their parents) their birth weights and weight at six months to determine if these weights follow the rule of thumb as discussed in class.

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### Learning Objectives

Students will:
• Complete a chart by doubling or halving numbers
• Compare data by use of vertical and horizontal bar graphs

### NCTM Standards and Expectations

• Pose questions and gather data about themselves and their surroundings.