• Category: Uncategorized
• Published Dated: March 1, 2015
• Written by: Susan

This was posted in 2013, but I like to re-post because these particular strategies from my books are all based on Addition Doubles facts. Once children understand and have memorized these Addition Doubles facts, 1+1, 2+2, 3+3, 4+4, 5+5, 6+6, 7+7, 8+8, and 9+9, you can introduce these strategies to teach the following addition and multiplication facts. Explanations for each of the four strategies are below.

1. Number in the Middle: 1+3, 3+1, 2+4, 4+2, 3+5, 5+3, 4+6, 6+4, 5+7, 7+5, 6+8, 8+6, 7+9, 9+7

2. Double +1: 2+3, 3+2, 3+4, 4+3, 4+5, 5+4, 5+6, 6+5, 6+7, 7+6, 7+8, 8+7, 8+9, 9+8

3. Doubles with multiplication: 2×2, 2×3, 3×2, 2×4, 4×2, 2×5, 5×2, 2×6, 6×2, 2×7, 7×2, 2×8, 8×2, 2×9, 9×2

4. 4 Fingers: 4×3, 3×4, 4×5, 5×4, 4×6, 6×4, 4×7, 7×4, 4×8, 8×4, 4×9, 9×4

Remember to always first make sure your student can show, by using counters or drawing lines or dots, what the math fact means.

Number in the Middle is explained in another post. Basically, ask the student, “What number fits between…?” For example: Once the student automatically knows 7+7 is 14, you can teach 6+8 and 8+6. Ask, “What number fits between 6 and 8?” 6, 7, 8. 7 fits in the middle. Double 7. 7+7 =14. 6+8 and 8+6 is 14.

Double +1 is demonstrated by showing the facts with counters or cubes. For example: After the student already memorized 4+4 is 8, teach 4+5 and 5+4. Line the 4 cubes next to the 5 cubes. Show that 4+4 is 8, and 1 more is 9. By doubling the lesser or smaller number, and then adding 1 more, the student will get the correct answer.
After the student memorized 8+8 is 16, show how 8+9 and 9+8 is 17. Line the 8 cubes next to 9 cubes. 8+8 is 16, 1 more is 17.

Doubles with multiplication is very simple after the addition Doubles are memorized. If you student only knows 2+2, 3+3, 4+4, 5+5, 8+8, then you can teach: 2×2, 3×2, 2×3, 4×2, 2×4, 5×2, 2×5, 8×2, 2×8.
I like to show this with two hands. For example: Have the student show two groups of 8. Ask them to place one group in each hand. Ask them to put their hands together and think about how much they have. 8+8 = 16. Two groups of 8 is the same as 8+8. Later, show that 2×8 is the same as 8 groups of 2, 8×2.

4 Fingers is fun to teach. Once your student memorized the Doubles facts, 3+3= 6, and 6+6 = 12, have your student show 4 groups of 3. Separate two of the groups to the left, and two of the groups to the right. Ask how much is on one side, (3+3 =6) and how much is on the other side, (also 3+3=6.) Then push the two groups together together. 6+6 =12. 4 groups of 3 =12. 4×3=12.

Then show that 3 groups of 4 is the same answer.

Another example using 4×7. 4 groups of 7. Students must first know 7+7 is 14, and 14+14=28. 4×7 and 7×4 =28.