Crossing Out Singles

Game

This game is a good context for the students to practise their basic addition and multiplication facts and to practise using efficient mental strategies for addition and multiplication. For example, when adding the first four numbers on Geoff’s board, the students could look for numbers that add up to 10 (3, 5, and 2 in the
second row or 6, 3, and 1 in the third row), or they could look for doubles (in the bottom row, double 3 is 6, double 6 is 12). When they are multiplying by the fifth number in each row, for example, 17 x 5 in the bottom row, they may calculate it as (20 x 5) – (3 x 5) or (10 x 5) + (7 x 5). Alternatively, they may calculate it as half
of 17 x 10.
After the students have played the game several times, encourage them to start thinking about strategies for winning the game. This strategic thinking is excellent mathematical work.
Many variations of this game are possible with only minor changes:

• Change the dice: use a 10-sided dice, a 10, 20, 30, 40, 50, and 60 dice, or, to simplify the game, a dice with two ones, two twos, and two threes.

• Change the rules so that the lowest score wins.

• Change the size of the board to make it more complex or simplify it to suit different groups of students.

Answers to Activity

Game
A game using addition and multiplication facts