Goal: Identify what a group of math fact cards has in common
Start two columnsEach group spreads out their cards, problem side up.


Take turns sorting On each turn, a player chooses a card and decides where it goes.
If needed, the Leader moves the card to the correct column. 

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.
From arithmetic to algebra in words
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.”
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.
Grades
Minimum number of participants
Suggested grouping
Time
Math
Materials
Prerequisites
Books about sorting and classifying