## Lesson: Measuring and Comparing LengthIntroducing the Concept

Helping children to develop their measurement skills is an ongoing task. Children begin by directly comparing the length of various items. Then they learn to measure length with nonstandard units. In the next lesson they learn to measure length in inches and centimeters.

Materials: paper clips of various sizes for each child, overhead projector

Preparation: Place 20 to 30 paper clips into plastic bags for each child or group of children. Within each bag, all paper clips should be of the same size. Eventually you will need enough bags of large paper clips for each child or group of children.

Prerequisite Skills and Concepts: none

• Say: Today we are going to learn about measuring length. We will start by comparing things to find out which are taller and which are shorter. Look around the room for things that are taller than I am.
Have the children list items that are taller than you. As they name an item, stand next to it to confirm that it is taller than you are.
• Say: Now, let's find things that are shorter than I am.
Have the children list items that are shorter than you. As they name an item, stand next to it to confirm that it is shorter than you are.
• Say: Comparing items is one way to talk about their height or length, but it doesn't give you much information. Look at all the things that are shorter than I am.
Discuss some of the items that are shorter than you are, but which are very different in length. For example, although both the children and a pencil are shorter than you are, each child is much taller (longer) than a pencil.
• Say: When you want to describe how tall or long something is, you can be more specific if you measure that item. Today we are going to use paper clips to measure things.
Pass out the bags of paper clips and have the children pour the clips out on their desks.
• Say: When you measure something, make sure the end of the first paper clip lines up with the end of the item. Keep adding clips until you reach the end of the object you are measuring. Then count the number of paper clips.
Place a marker on the overhead and demonstrate how to measure it by lining the paper clips up end to end. Discuss how to estimate when the paper clips don't match the end of an item exactly. This will help children understand approximations.
• Ask: How many paper clips long is the marker?
• Say: Now, measure the length of your math book. Measure it this way (run your hand along the spine) and remember to line up the first paper clip with the edge of the book.
Circulate to see that children are measuring the length (not the width) of the book and that they are lining up their paper clips properly.
Answers will vary. On the chalkboard make a chart of 5 responses for the children to see the results.
Length of Math Book in Paper Clips
Name Number of Paper Clips

• Say: This is interesting. We all have the same math book, but we have different answers for the number of clips that were needed.
• Ask: Why do you think that we got these different answers?
Lead children to see that not everyone has the same size paper clips. Although the answers were different, they could all be correct, because the unit of measurement was different.
• Ask: What could we do to make sure that everyone gets the same measurement?
Lead children to decide that everyone should use the same size paper clips when they are measuring. That way, everyone should get the same result.
• Say: Let's all use the large paper clips and measure our math book again. If you have small paper clips, raise your hand and I will give you a bag of large ones.
Have children trade in bags of smaller paper clips for large ones. Then have them re-measure their books.
• Ask: Who can tell me the number of clips they used to measure the book this time?
Ask several children, and list their responses on the chalkboard. All answers should be within one paper clip of each other.
• Ask: Is it better to use the same size clip to measure, or is it just as easy to measure with a group of different-size clips?
Children should respond that it is better to use just one size.
• Say: Let's try measuring some other items with the large paper clips. (Pass out unsharpened pencils.) Let's measure these pencils.
Give children time to measure the pencils.
• Ask: In paper clips, how long is the pencil?
Answers will vary, but they should all be close. Repeat this process with various items in the classroom.
• Ask: Why is it important that everyone use the same size paper clips to measure?
Lead children to say that if they used different-sized paper clips, their measurements would be different.