Build Number Sense Playing This Addition Game
One of my favorite math games for elementary math students to play is “Close to 100″. This lesson and game can be found in TERC math Investigations books for third grade. The game instructions, number card blackline masters, and score sheets are in the unit Mathematical Thinking. In this game one student of a pair draws six numeral cards (0-9) without looking from a deck and selects four cards to use. With these four cards students are to build two two-digit addends to find a sum as close to 100 a possible. The player’s score is how far away from 100 the sum is. For example if the sum is 102, the score is 2. If the sum is 95, the score is 5. Each player totals up his scores at the end of the game, and the player with the least score wins. What I like so much about this game is that students are practicing facts, learning place value, buildingnumber sense, adding, and subtracting while they are engaged in cooperative learning. The only quibble I have with this lesson is that the only assessment to be gathered is informal teacher observation. To make up for the lack of assessment provided in the lesson, I recommend that after playing the game to give students a scenario in which they draw six cards. Have students write about which of the cards they would chose to use to get as close to 100 as possible. To differentiate this lesson, struggling students can pull only 5 cards and choose 3 number cards to make 20 (First grade Mathematical Thinking book), or advanced learners can pull 8 cards and choose 6 to build 1000 (Fifth grade Mathematical Thinking book).
See an example of this game here: http://www.pearsonschool.com/live/images/custom/investigations/Investigations_widget1.html.