Addition Within 20 Error Detective

Answer Key - Grade 1 Math Worksheet - Building Confidence

Circle the answer, or write the answer on the line.

1. 1.

   A student wrote 4 + 6 = 10. Is it correct?

   • yes
   • no
2. 2.

   A student wrote 4 + 2 = 5. That is a mistake. What should it be?

   6
3. 3.

   Only one of these addition facts has a mistake. Which one?

   • 4 + 4 = 8
   • 6 + 6 = 13
   • 8 + 3 = 11
4. 4.

   A student wrote 2 + 5 = 6. Is it correct?

   • no
   • yes
5. 5.

   A student wrote 5 + 3 = 9. That is a mistake. What should it be?

   8
6. 6.

   Only one of these addition facts has a mistake. Which one?

   • 4 + 6 = 10
   • 6 + 6 = 12
   • 4 + 7 = 10
7. 7.

   A student wrote 6 + 5 = 11. Is it correct?

   • yes
   • no
8. 8.

   A student wrote 6 + 3 = 8. That is a mistake. What should it be?

   9
9. 9.

   Only one of these addition facts has a mistake. Which one?

   • 7 + 4 = 11
   • 6 + 3 = 8
   • 7 + 3 = 10
10. 10.

    A student wrote 4 + 3 = 6. Is it correct?

    • yes
    • no