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## Chapter 21

### Part 1: Home and School Investigation

Send the Letter to Family (PDF file) home with each child. Once all the children have brought in grocery store ads, put the children in pairs. Ask the children to find as many different ways as they can to combine two grocery store items and to find the total cost of each combination. Ask them to record what they find. You may need to review that ¢ stands for cent and that one penny is worth 1¢. A good time to do this activity is after Lesson 5 on two-digit addition practice.

### Part 2: Be an Investigator

A good time to do this investigation is after Lesson 5 on two-digit addition practice.

#### Introducing the Investigation

Tell the children that they are going to play a game in pairs. Show the children the cards you have made from the Investigator Worksheet. Tell them that each child will draw two of these cards. Each child will make a prediction of who will get the greater number when the numbers in each set of two cards are added. Once they make their predictions, the children do the addition, check each other's addition, and then see who got the greater number. Whoever predicted correctly scores a point. That means that in each round, both children could score a point, just one of the children could score a point, or neither of the children could score a point. Tell the children to keep track of their own score on a separate piece of paper by making a tally mark for each correct prediction.

#### Doing the Investigation

Watch children as they play the game. Make sure that they understand how to play and are keeping track of the score.

After the children have played the game, ask them to talk about how they made their predictions.