Lay cards face-down randomly in a 5 × 8 rectangle.
Explain that the goal is to match cards of the same number. Colour/suit do not matter.
For each round, students turn over one card and try to find a matching card.
Introduce the advanced version, if appropriate.
Explain that the goal is to find the numbers that add/subtract to a certain sum/difference (chosen from a number between 2-20).
Give an example, such as 5. Ask students for different number pairs for that sum (e.g., if the chosen sum = 5, players should aim for Ace + 4 or 9 – 4; if the chosen difference = 3, players should aim for pairs such, as 6 – 3 and 1 + 2).
When all pairs for the predetermined difference have been found, facilitate a discussion about how quantities can be composed and decomposed.
Challenge the students play the game in pairs.
Afterward, hold a discussion to extend student thinking. Here are some sample questions:
How did you know these pairs were correct?
What strategies did you use to add/subtract the two cards together?
What techniques did you use to remember where the cards were?
Why would there be more possible pairs for a larger difference (i.e., 10 versus 5)?
Do the children select the exact card that they were looking for?
Are students counting the number of symbols on the card? If so, are they using one-to-one correspondence? Are the students recognizing the numbers on the card?
Are the children using their fingers to count? Are the children counting up or counting on when they choose their pairs?
Do the children use certain memory strategies to determine if the pairs create the predetermined sum?
Do the children use mathematical language to talk about the cards?
Compose numbers up to and including the number 50 using different strategies.