Addition Within 20 Error Detective

Answer Key - Grade 1 Math Worksheet - Challenge Me

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

1. 1.

   A student wrote 4 + 16 = 20. Is it correct?

   • no
   • yes
2. 2.

   A student wrote 12 + 6 = 19. That is a mistake. What should it be?

   18
3. 3.

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

   • 14 + 5 = 19
   • 15 + 2 = 17
   • 11 + 3 = 15
   • 9 + 2 = 11
4. 4.

   A student wrote 5 + 9 = 12. Is it correct?

   • no
   • yes
5. 5.

   A student wrote 8 + 10 = 20. That is a mistake. What should it be?

   18
6. 6.

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

   • 17 + 3 = 20
   • 14 + 3 = 18
   • 4 + 12 = 16
   • 7 + 11 = 18
7. 7.

   A student wrote 17 + 2 = 19. Is it correct?

   • no
   • yes
8. 8.

   A student wrote 8 + 6 = 16. That is a mistake. What should it be?

   14
9. 9.

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

   • 16 + 4 = 20
   • 15 + 3 = 18
   • 5 + 7 = 12
   • 11 + 5 = 15
10. 10.

    A student wrote 12 + 4 = 14. Is it correct?

    • no
    • yes