Thursday, December 12, 2013

One of the biggest math challenges Lauren faced in second grade is addition and subtraction with regrouping (aka: carrying and borrowing). She grew bored with her practice worksheets long before she proved that she could confidently and easily do the proper calculations

I dreamed up this simple game so that we would have a bit more fun while she practiced. One key to our success was that I played alongside her. As I worked my problems, I modeled some of the tricky aspects of regrouping. She caught on as I talked through my thinking process, and before long she was narrating her work with phrases borrowed from my monologues. Instead of growing frustrated with a subtraction problem that needs her to borrow, she'll rather cheerfully say, "Mr. Ten, Mr. Ten, can I borrow ten ones from you?"

Materials:
Three dice
Pencil
Paper

1. Roll three dice. Arrange the three digits to make the largest number possible. Everyone writes this number on the top of the paper and it becomes the target score for the round.

2. Write the three digit number at the top of the paper.

3. Roll two dice and write down the largest two-digit number possible.

4. Roll the dice again and write down a second two-digit number.

5. Add the two numbers together (regrouping as necessary).

6. If you rolled doubles, then take another turn. Otherwise pass the dice to the next player.

7. On the next round, only roll the dice one time and add that two-digit number to the previous total.

8. The first person to reach the goal number written at the top of the page is the winner!

Subtraction version:

1. The initial subtraction problem starts with the three digit number written at the top of the paper.

2. On each turn, subtract the two digit number rolled until a player rolls a number too large to make a subtraction problem.

We found it easiest to skip a line between the problem and the answer. The blank line gives a little extra room to show the regrouping work.

For students just starting to grasp the concept of regrouping, a single-digit number could be added or subtracted on each turn.