Adding by 9 is Week 3 for mastering basic math addition plan for Grade 1. Compared to the previous weeks, Week 3 will just be for addition with 9. It looks like a big number to add but there’s a cool strategy that makes it faster and easier to master. Once the child masters this week’s topic, the rest will look easy.
Adding by 9 Teaching Strategies
The strategies below are just suggestions. It may work or may not work with your child. I suggest using one strategy at a time. If the strategy already works, stick to it. Having too many strategies can be confusing also. If your child has developed their own strategy to consistently arrive to the correct answer, use it as well. In fact, that may be the best strategy!
- Recognize that 9 can be written as 10-1. By knowing this relation, the child will be adding by 10 and then subtract by 1 which is faster. It will take two steps but it’s more familiar to the child. For example, 9+5 can be written as 10+5-1. The child will now be adding by 10 first, or 10+5 which is 15. Then subtract by 1, or 15-1, to arrive to the correct answer which is 14. Be sure to subtract by 1. Here’s a video about adding by 9 to explain this strategy. If you need to review adding by 10, check out our Adding by 10 worksheets here.
- Point out the pattern that when adding by 9, the ones digit in the sum is always one less than the number added to 9. For example 9+5 = 14, the 4 is one less than 5.
- Emphasize the commutative property of addition. It simply means that the order of the numbers (or addends), does not affect the answer. Thus, the answer for 9+7 is the same as 7+9.
Adding by 9 Worksheets
Use the worksheets below to practice adding by 9. I recommend having 2 worksheets per day only.
The first four worksheets below are good for 2 days of practice.
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The next four worksheets has a line for TIME. You can use this to time how fast your child can answer the 20 items correctly. The goal is to be fast and accurate at the same time. Thus, if the child makes a mistake, 10 seconds is added to the total time.
No need to set a time limit. Just use the time as a comparison with previous worksheets.
These timed tests are optional. You may opt not to take note of the time. Some experts believe that timed tests have a negative impact on kids. Aim for accuracy over speed.
- Speed Test – Adding by 9 Worksheet #1
- Speed Test – Adding by 9 Worksheet #2
- Speed Test – Adding by 9 Worksheet #3
- Speed Test – Adding by 9 Worksheet #4
Adding by 9 is Week 3 of the 8-week Basic Math Addition Mastery Plan. By the end of Week 3, the child has already mastered about 70% of all the addition facts!!!
Read also our 8-week Basic Math Addition Mastery Plan.
