Goal: Identify the secret rule that a player uses to sort cards
Grades: (K, 1, 2 in variations) 3, 4, 5, 6, 7 Group size: 2 or more Time: 10 minutes or less
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Materials: Math fact cards (1 deck per group of 2–6) Prerequisites: Some familiarity with arithmetic facts |
Distribute decks of math fact cards to groups. Players spread out the cards problem side up, and decide who will be the Chooser.
The Chooser secretly picks a rule that fits some—but not all—of the cards. The rule, based on the answers to the problems, should involve more, less, or equals. For instance: The answer is more than 40.
To start the game, the Chooser finds two cards that fit the rule and two that don’t, puts them into two groups, and tells the players which group fits the rule.
Players take turns choosing another card from the layout and placing that card in one of the two groups. The Chooser announces whether this placement is correct, moving the card as needed to the right group
2. Guess the rule
After three players in a row have placed a card correctly, everyone takes a turn guessing the rule.
The winner is the player who guesses correctly. If no one guesses correctly, go back to step 2.
Variations
More or Less (Grades K, 1, 2, 3, 4)
Spread out the cards answer side up, instead of problem side up. The Chooser picks a rule involving the numbers face-up on the cards. For instance: The numbers are more than 30. Or, The numbers are less than 20.
Use a deck of playing cards. The Chooser picks a rule involving the suit (heart, diamond, clubs, spades) or number on the card, for instance: The suit is diamonds. Or, The number is 4.
Books and Other Resources
Book ideas to come!
From arithmetic to algebra
As children reason about what a set of math facts has in common, they investigate patterns in arithmetic.
In this game, children describe patterns in words, for instance “The answer equals 3.” When they study algebra, they will learn to describe similar patterns with notation: “A – B = 3.”
ConnectionsMental math and math facts
Everyone forgets arithmetic facts from time to time, but people with good mental math skills can reconstruct forgotten facts using knowledge of numbers, number patterns, and relationships between facts—all skills that children develop in this activity.
For instance, if you can’t remember the answer to 5 + 7, one strategy is to reason that 6 + 6 is 12, therefore 5 + 7 must also be 12—one addend is 1 less than 6, and the other is 1 more than 6.
Mental math skills are also useful in figuring out upcoming dates. Say it’s Wednesday the 19th, and you need to know the date a week from Friday. You can use mental math to figure it out: 2 days from now is the 21st, and 7 days after that is the 28th.
©2008 TERC, Cambridge, MA. All rights reserved.
