## Subtraction Game

Zebra Bump

**The Essence of the Game:**

Two players race around the outside track answering subtraction algorithms as they go. On giving the correct answer the students place one of their counters on the algorithm’s answer in the center of the board. The game is ideal for practicing Subtraction Basic Facts and for developing number strategies associated with Subtraction.

**What You Need:**

2 Players

1 Bump Board

2 playing pieces (e.g. counters, coins, small rocks, game pieces)

5 transparent counters per player

1 die marked 1-6

**Game Set-Up:**

Players sit facing the board with their 5 counters in hand. Each player chooses a different tree as their starting point on the board and places their game piece on it.

NB The students must decide if they go around the board clockwise or anticlockwise. (For no other reason but to provide a context to learn the terms ‘clockwise’ and ‘anti-clockwise’) hehehe

**How to Play:**

1. The student with the longest middle name goes first.

2. Player One throws the die and moves their counter the corresponding number of spaces.

3. Player One answers the algorithm they land on aloud and places a counter on the difference in the middle of the board.

4. Player 2 then repeats steps 2 & 3.

**The Bump Rule: **

If the answer to an algorithm is already covered by an opponent’s counter, the current player may BUMP the counter off the board and return it to their opposition’s hand. The current player then places their counter on the answer.

**The Locked-In Rule:**

If a player already has one of their counters on an answer then answers another algorithm that requires them to put their counter on that space, they can. The player places the second counter on top of their first to make a pile of two. This space is then ‘locked in’ and pieces cannot be bumped from the board or have any more counters added to them.

**How to Win:**

The first player to use up all their counters wins the game.

**Organizational Hints:**

– Have the students drop the die onto a piece of A4 paper to eliminate, ‘wild throws’ and the disruptions they cause. If the die rolls off the piece of paper then the player misses a turn.

– Have students drop the die onto an A4 piece of felt to cut down noise. If a die goes off the mat the turn is disallowed.

– List 5 reason why it might it be a good idea for players to check each other’s answers for accuracy?

**Conduct Number Talks Before and After the Game. **

A ‘Number Talk’ is a 5 to 15-minute class discussion. It focuses on the efficient use of number strategies to solve problems. The teacher and students talk about problem-solving strategies to explore and expose the group to new ways of thinking. The talks serve to deepen mathematical understandings and develop computational fluency.

Strategy 1 – Count back only 1, 2, and maybe 3. No more. It is inefficient.

Strategy 2 – Use Addition to solve Subtraction. How is this done?

Strategy 3 – Use facts you already know. What could this mean? e.g. Addition Doubles

Strategy 4 – Count through 10. Demonstrate how to do this.

Self-talk – How many more to make___?

– Use Addition to solve Subtraction.

**A Possible Number Talk Strategy: **

Write up any algorithm the students will encounter during the playing of the game.

– Have the students discuss honestly with a partner how they would solve it.

– How would your teacher want you to solve it? Why?

– Which strategy do you like? Why?

– Do you have another way of working this out that is quick and accurate? Share it with us?

**Base Number Talks on Observed Behaviours: **

– When you see students

*more than three numbers to solve the algorithms, encourage the practicing of more efficient number strategies.***counting backward**– The game flows well when you skip count going around the board rather than counting individual spaces. Give it a go. What do you think?

– Using an ‘efficient strategy’ means getting to the answer as fast as possible by using appropriate Math strategies.

– When you throw a 6 do you count by ones or twos? Which one is quickest and still accurate? Demonstrate.

– What different ways can you use to skip count if you threw a 5? 2+2+1, 1+2+2, 2+3. Is this faster than counting one at a time?

– Tell your partner what strategy you could use for when you throw a 4.

**Possible Journal Reflections:**

– I enjoyed playing the Math game today because _____________

– I did not enjoy playing the Math game today because __________

– While playing the Math game today I figured out ________

– After playing this Math game I now can __________

– Based on the way I felt today in Math I need to __________

– What did you discover about your use of Subtraction strategies while playing this game?

– On a scale from 1 to 10 I rated my Math work a ______ today because________

– Make a list of the patterns you saw when playing these games

**Game Boards Included in this Download:**

Board 1: Use knowledge of Addition Doubles Facts to solve the Subtraction algorithms.

Board 2: Use knowledge of Addition Doubles Plus One Facts to solve the Subtraction algorithms.

Board 3: Use knowledge of Addition Doubles Plus Two Facts to solve the Subtraction algorithms.

Board 4: Use knowledge of Bonds to 10 Facts to solve the Subtraction algorithms.

Board 5: Use knowledge of Bonds to 20 Facts to solve the Subtraction algorithms.

Board 6: Use knowledge of Bonds to 20 Facts to solve the Subtraction algorithms.

Board 7: Use a strategy to subtract 9 from a number.

**Also Included in this Download:**

– A PowerPoint file with all the game boards for easy discussion

– Game Rules

– Teaching Notes

– Possible Math Journal Reflections

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