Target 0: Subtraction

Summary

Students use base 10 blocks to represent subtracting 2-digit numbers in a race to be first to reach 0.

Curriculum content

• Subtraction of 1-digit numbers from 2-digits
• Place value up to 100

Materials

Card sets

• 1 set of Mathletics number cards 1 to 9 1-9

Concrete

• Base 10 blocks (ones, tens, hundreds)

Printables

• Place value mat Download place value mat 

How to play

Set up

1. Arrange students into pairs or small groups.
2. Shuffle or mix up the cards and place them in a pile face down.
3. Give each student a place value mat and base 10 blocks.
4. Students place a hundred block on their place value mats.

Rules

1. Player 1 chooses the top card and takes that number away from their starting hundred.
2. Players will need to exchange their hundred to make 10 tens and exchange a ten for 10 ones.
3. The card is returned to the bottom of the pile.
4. Players take turns selecting a card and subtracting the value from their place value mat.
5. The winner is the first player to reach 0.

Variations

CHANGE it down

• Reduce the starting number to 50.
• Work in collaborative pairs to assist in verbalizing thinking.

CHANGE it up

• Students record calculations throughout the game.
• Use numeral cards 1 to 20.
• Make the winner the player that reaches 0 exactly and players can choose to add or subtract.
• Extend the starting value to 200.

What to look for

• Are students able to represent numbers accurately using base 10 blocks?
• Do students swap hundreds for tens and tens for ones at the appropriate time?
• Are students able to use mathematical language to explain their representation?