Rule It Out

Goal: Identify what a group of math fact cards has in common

step 1

Start two columns

Each group spreads out their cards, problem side up.
Groups pick a Leader. The Leader secretly decides on a category that fits some—but not all—the cards. Then the Leader

  • starts a column with two cards that fit the category
  • starts another column with two cards that don’t.
fits the category: 4+4, 4+2; doesn't fit the category: 3+8, 4+7
step 2

Take turns sorting

On each turn, a player chooses a card and decides where it goes.

talk aboutWhy do you think 1 + 3 fits the category? What do the cards that fit the category have in common?

If needed, the Leader moves the card to the correct column.

kid in overalls
step 3

Ask about the category

After everyone has had two turns, players may each say what they think the category is. If no one gets it, go back to step 2.


Use playing cards (easier). The Leader picks a category involving the suit or number on the cards.

Mix it up (harder). Play with a selection of cards that involve addition, subtraction, multiplication, and division.


Math Spotlight

From arithmetic to algebra in words

3 rows of cards

In this game, children look for what a set of math facts in common. They describe the patterns they find with words. For instance, “The answer is 3.”

When they study algebra, they will learn to describe similar patterns with notation: “A – B = 3.”


Everyday Connections

Mental math and math facts

Mental arithmetic involves knowing math facts and a lot more! When children have a chance to reason about math facts—as they do in this activity—they explore:

Relationships between math facts: 6 + 6 is 12, so 5 + 7 must also be 12. 5 is 1 less than 6, and 7 is 1 more than 6.

Patterns: If 8 – 5 is 3, then so is 9 – 6 (adding 1 to each), 10 – 4 (adding 2 to each), 11 – 5... and so on.

In every day life, people also need to know when and how to use arithmetic. 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. While it’s vital to know how to add, you also need to know how to use addition in whatever situations you face.

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  • 2-6+

Minimum number of participants

  • 2

Suggested grouping

  • divide into groups of 2-4


  • 10 minutes or less per game


  • arithmetic; using logic; number patterns


  • Math fact card decks: 1 per group
    Easy. addition with answers up to 10
    Medium. addition or subtraction
    Hard. multiplication or division


  • some familiarity with arithmetic facts

Books about sorting and classifying

  • Max’s Words. Banks, Kate. (Farrar, Straus and Giroux, 2006).
  • Math-terpieces. Tang, Greg. (Scholastic Press, 2003).