## Thursday, February 19, 2009

### Math problem of the week: 2nd Grade Trailblazers vs. Singapore Math

1. The final assignment in 2nd grade Trailblazers Student Guide Book 2, Unit 11, Ways of Subtracting Larger Numbers, p. 299:

Difference War

Players: two or more

Materials: digit cards or regular playing cards, paper, pencil (If you use the regular playing cards, remove the tens and face cards and use the aces for the number one.)

Winner: Player with the most cards at the end of the game.

Rules:
*Deal out four cards to each player.
*Each player makes a subtraction problem with the four cards.
*Each player solves his or her subtraction problem.
*The player whose answer is the smallest takes everyone's cards and puts them aside.
*Keep dealing four more cards to each payer and making problems.
*When all the cards are gone, the player who has collected the most cards wins.

Play several games. Then, write about what happened. Tell how you think you can win.

2. The final assignment in 2nd grade Singapore Math Primary Mathematics 2B, Unit 7, Addition and Subtraction, p. 25:

Subtract.
(a) 180 - 99 =
(b) 302 - 99 =
(c) 556 - 99 =
(d) 848 - 99 =
(e) 205 - 98 =
(f) 467 - 98 =
(g) 780 - 98 =
(h) 632 - 98 =

3. Extra Credit

Which activity is more mathematically engaging, and to whom?