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?