Grade
2

How Many Are Hidden? Buttons in a Bag

Both pictures have the same number of buttons.

How many buttons are hidden in the bag? How do you know? How can you finish the equation to make it true?

The picture on the left shows 4 blue buttons and 16 red buttons. The picture on the right shows 8 blue buttons and an unknown number of red buttons inside a paper bag. Blue 4 + red 16 = blue 8 + red blank.

Look at the blue numbers on both sides of the equation. What do you notice? What about the red number?

In the equation blue 4 + red 16 = blue 8 + red blank, the 4 changes to 8. How does the 16 change in a true equation?
  • Now there are more than 20 buttons. You get to decide how many!
    How many might be hidden in each bag? How do you know?
  • Finish the equation to make it true.
    What do you notice about how the numbers changed this time?
The picture on the left shows 14 blue buttons and an unknown number of red buttons inside a paper bag. The picture on the right shows 10 blue buttons and an unknown number of red buttons inside a paper bag. Blue 14 + red blank = blue 10 + red blank.
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