LO: To estimate and check the reasonableness of answers in addition and subtraction problems calculations by rounding numbers.

 LO: To confidently explain how and why calculations are correct using mathematical reasoning.

Warm up! 

I'm thinking of a 2-digit number.

It is greater than 40.

It is less than 70.

The digits add to 9.

Discuss:
Did we just randomly guess?

Strategy: Guessing and Checking

language:

• Guess

• Check

• Too high

• Too low

• Adjust

• Strategy

• Reasoning