Math Investigations

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Chapter 7

Part 1: Home and School Investigation

Send the Letter to Family (PDF file) home with each child. Once all of the children have brought in the drawing of their castle door, have each child show his or her drawing to the class. Have volunteers point out the lines of symmetry. Create a Castle Door bulletin board from all of the designs. A good time to do this activity is after Lesson 4 on symmetry.

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 2 on sides and vertices.

Materials

Introducing the Investigation

Hold up the Investigator Worksheet. Ask questions about the design on the worksheet such as:

  • Can anyone find a shape with four sides in this design?
  • How many sides does this design have?
  • Do you see any shapes you can name in this design?

Say, We are going to do an activity where we color this design so that no two shapes that are side-by-side have the same color. Demonstrate this by coloring two shapes that are side-by-side with the same color. Point out that this is an example of what children do not want. Then color two shapes that are side-by-side using two different colors. Point out that this is an example of what children do want. Point to the shared side between the two shapes and say, This side is the same for both of these shapes, and there is a different color on each side. Tell children you want them to color the design so that no two shapes that are side-by-side have the same color and you want them to do this using the fewest number of colors.

Put children in pairs to work on this activity.

Doing the Investigation

As you watch children doing the activity ask questions such as, Are any shapes that are side-by-side the same color? This will help children remember the rules.

When children are finished, ask them what they found. Children may have found a way to do it with five or more colors. If so, ask questions such as, Did anyone find a way to do it with fewer than six colors? Keep asking until you get an example with four colors. Get children who used more than four colors to make a new design with four colors. Display the designs on a bulletin board.


Houghton Mifflin Math Grade 2