Doubles Plus 1

Teaching Notes

Students add 1 to a doubles fact to find the sum.

Before You Begin

• Adding Doubles

Teaching Steps for Parents and Teachers

1. Compare 6 and 7. Notice that 7 is 1 more than 6.
2. First, calculate 6 + 6 = 12.
3. Since 7 is 1 more than 6, add 1 to 12.
4. Write 6 + 7 = 13 and explain how the doubles fact helped.

Worked Examples

6 + 7 = 6 + 6 + 1 = 13

1. Since 6 + 6 = 12, adding one more gives 6 + 7 = 13.

Answer: 13

Common Mistakes and How to Help

Adding 2 to the doubles fact

Compare 6 + 6 with 6 + 7. Only one addend increased by 1.

Correcting the answer without explaining why

Do not increase both addends by 1. Add only 1 to the doubles sum. Have the student start again at the first incorrect step.

Questions to Check Understanding

• How much greater is 6 + 7 than 6 + 6?
• What does each number in the worked example represent in the original problem?
• Can you use the same method when the numbers change?

Practice Advice

Work through the example together and have the student explain why the answer is 13. Ask the student to explain the first two problems aloud, then solve the next three independently. Review the intermediate steps as well as the final answers. If an error repeats, return to the difficult teaching step before assigning more problems.

Next Practice

• Choose New Numbers for more practice with the same conditions. Ask the student to explain the reasoning as well as give the answer.
• If the student cannot explain the method independently, use smaller numbers to explore the same relationship first.