Math Investigations

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Chapter 9

Part 1: Home and School Investigation

Send the Letter to Family (PDF file) home with each child. At snack time the next day, make sure all children have brought a snack. Provide children who could not bring a snack with bread (or popcorn) to participate in the activity. Have the children show the snacks they have brought in and how the snack has been separated into fourths. For example, someone might show a sandwich that has been cut into four equal parts. If one of the children brings in a group of raisins (or nuts, cereal, etc.) separated into fourths, there will be an opportunity to do some informal work with the concept of fractions of a group.

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 3 on wholes and parts.

Materials

  • blank paper of different sizes
  • crayon

Introducing the Investigation

Tell children they are going to be using their knowledge of fractions to make some predictions. Ask, What is a prediction? Throughout the discussion, help the children understand that a prediction is like a guess; with a prediction, you use the things you know to help you make a good guess.

Doing the Investigation

Show children a blank piece of rectangular paper. Ask children to watch as you fold it in half. Color a section (made from the fold) with a crayon.

Say, I am going to unfold this paper. What fraction do you think will tell how much of the paper is colored in? Let students make guesses.

Unfold the piece of paper. Ask, How much of the paper was colored in? (one half)

paper that has been folded in half and is now unfolded with one half colored

Ask children to see if they can find a piece of paper where the half would be a different size. With the children watching, take some of these pieces of paper and fold them in half. Compare that half to the half of the original piece of paper.

Now take another piece of rectangular paper of the same size as the original. Ask students to watch as you fold it in half and then fold it in half again. Color a section (made from the fold) with a crayon.

Say, I am going to unfold this paper. What fraction do you think will tell how much of the paper is colored in? Let students make guesses.

Unfold the piece of paper. Ask How much of the paper was colored in? (one fourth)

paper that has been folded into fourths and then unfolded with one fourth colored in

Repeat with a larger rectangular piece of paper. Compare the one-fourth section on this piece of paper with the one-fourth section on the smaller piece of paper.

2 rectangular pieces of paper of different sizes folded into fourths and unfolded. One fourth is colored in on each rectangle

Ask, If these were pieces of cake, which piece would you want? (Most children will likely say they would like the larger piece.) Say, Each of these parts that was colored in is one fourth. Why do you think one part is bigger than the other? In the discussion, try to get at the idea that the size of the part depends on the size of the whole.

Extending the Investigation

You can do this same investigation by folding a circle into halves and fourths.


Houghton Mifflin Math Grade 2