Subtract Within 20 Game

Subtract Within 20 Game
Learning subtraction using a ten-frame is a powerful way to visualize “taking away” and “bridging” back to ten. It helps move students away from counting on fingers to seeing numbers as chunks.
Scroll down the page for a more detailed explanation.
 
Check out these other Ten-Frame games:
Ten Frame Subtraction (within 10)
Subtracting from 10
Subtracting within 20
 

 

How the “Subtract Within 20 Game” Works
The game presents subtraction problem where a 1-digit or 2-digit number (subtrahend) is subtracted from 2-digit (minuend). The student must determine the difference by visualizing the dots being removed from the minuend.

1. Analyze the Problem
   The game presents a math sentence like 13 - 6 = ?. On the screen, you will see the first number (13) represented by the full first frame and the second frame has 3 dots.
   
2. Calculate the Difference
   Before you click anything, look at the dots.
   How many dots will be left after removing 6 dots? (7)
   
3. Choose Your Answer
   Select the correct number from the grid at the bottom.
   If you are correct: The number turns green, and you’ll hear a happy chime.
   If you are incorrect: The number turns red, and the game will highlight the correct answer in green to help you learn for next time.
   
4. Watch the “Cross-Out” Animation
   This is an important part of the game. Regardless of your answer, the game will visually prove the math:
   The game will cross out the number of dots according to the subtrahend. By seeing the “Cross-Out” animation, you can immediately see why the correct answer is what it is.
   
5. Review and Move On
   The game pauses so you can look at the result. Once the dots are crossed out, you can easily see what remains. When you are ready, click the “Next Problem” button to start a new challenge.
   
   The “Subtracting Through Ten” Strategy
   The game is designed to model how to subtract through ten. When a student subtracts (for example, 13 - 6), the animation follows a specific sequence:
   Remove from the “Extra”: It first crosses out the 3 dots in the second frame.
   Break into the Ten: Since 3 more still need to be subtracted, it moves to the first (full) ten-frame and crosses out 3 more from the end.
   The Result: The student sees 7 dots left in the first frame.
    
   

This video gives a clear, step-by-step approach to learn subtraction within 10 using a ten-frame.

• Show Video

 

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