Mental Math
What is mental computation?
Doing arithmetic in your head without paper, pencil, or calculator.
What is estimation?
Making a close guess instead of an exact answer.
What is decomposition or breaking apart?
46 + 38 can be solved by adding 40 + 30 and 6 + 8 separately.
➡️ What is decomposition or breaking apart?
46 + 38 can be solved by adding 40 + 30 and 6 + 8 separately.
What is place value?
A student who adds 38 + 7 = 315 might be misunderstanding this concept.
What is decomposition or splitting?
This strategy involves breaking numbers apart into easier chunks.
What is reasonable?
Estimation helps check whether an answer is correct.
What is compensation?
Changing a problem into an easier but equal one, like 99 + 26 → 100 + 25.
What is compensation?
Changing a problem into an easier but equal one, like 99 + 26 → 100 + 25.
What is borrowing or regrouping?
Writing 52 – 38 = 26 shows confusion with this concept.
What is rounding?
Estimating
What is front-end estimation?
A “front-end” estimation adds only the leading digits.
What is multiplication?
Doubling and halving are strategies used in this operation.
What is multiplication?
Doubling and halving are strategies used in this operation.
What is an unreasonable answer?
When students forget to estimate, they might not catch this kind of mistake.
What is using known facts or patterns?
Knowing that 7 × 8 = 56 helps you solve 70 × 8 quickly.
What is rounding estimation?
This estimation strategy rounds numbers before combining them.
What is the commutative property?
This strategy involves changing the order of numbers to simplify.
What is the commutative property?
This strategy involves changing the order of numbers to simplify.
What is conceptual understanding?
Overreliance on memorized procedures can block this.
What is number sense or reasoning?
Being able to explain your thinking while computing mentally shows this.
What is compatible numbers estimation?
When multiplying 19 × 42, estimating 20 × 40 = 800 is an example of this.
What is strategy flexibility?
Students need this skill to select the best method for a given situation.
What is strategy flexibility?
Students need this skill to select the best method for a given situation.
What are the discussion or sharing strategies?
A good way to correct misconceptions is through this classroom practice.