Grade 3 starts off the year with addition and subtraction. You may see strategies that are different than what you were taught. Having a variety of strategies is important to developing deeper understanding of the operations.
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Mastery of the addition and subtraction facts is critical! Check out my "tips for learning the facts" on the drop down menu.
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Adding one number in parts
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This strategy using counting on from one number. Students generally add on the tens and then the ones. Watch AO solve 35 + 29. She is using an "open number line" to keep track of her thinking.
Adding By Place
This strategy involves adding the tens , adding the ones, and combining both parts.
If students can use this strategy effectively, they will be able to understand and apply the standard addition algorithm later on.
Show all Totals
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This strategy is really the same as Adding By Place (see left) but the recording looks a little bit different. It is a little more of a shortcut.
New Groups Below - This strategy may be introduced later.
This strategy uses place value and is similar to the "carrying" method that many parents have been taught.
New Groups Above- This strategy may be introduced later.
This strategy may be most familiar to parents! It is also called "carrying" or "regrouping" and it is a strategy based on place value.
SUBTRACTION STRATEGIES
Subtract in Parts - Shown here with 2 digits but this strategy can be used with three digits too!
Using Place Value Drawings
This strategy is a great way to show understanding!
Subtracting by Place Value- with or without regrouping (also called Ungrouping)
It is very important that students can relate this strategy to the place value drawings above. Teachers often delay teaching this strategy as it is a 4th grade standard.
