## Chapter 15

### Part 1: Home and School Investigation

Send the Letter to Family (PDF file) home with each child. Once all the children have brought in a picture of fingers showing a number, work with the children to sort the pictures. Put together all the pictures that show the number 11, that show the number 12, and so on. You might want to display the pictures in groups throughout the classroom. A good time to do this activity is after Lesson 5 on numbers 19–20.

### Part 2: Be an Investigator

A good time to do this investigation is after Lesson 5 on numbers 19–20.

#### Materials

- counting cubes, paper clips, or another kind of small object that can be used for non-standard measurement

#### Introducing the Investigation

Choose something such as counting cubes or paper clips to be used as the unit of measure. Pick an object in the classroom that the children can measure. Look for something that has a length between 10 and 20 units.

Tell the children that each of them is going to measure the length of his or her foot. First, have everyone guess what the length will be and write the guess at the top of a piece of paper. Then have each child measure the length of his or her foot and write down the actual measurement at the bottom of the paper. Then have the children compare their answers.

#### Doing the Investigation

Observe the children as they measure. Make sure that they are putting the measuring unit end to end and that they are counting correctly.

#### Extending the Investigation

Have the children measure other objects in the same way.