One more is when there is a greater amount by one or another item in the set.

One less is when there is a smaller value by one.

The result of subtracting one number from another, How much one number differs from another.

A group of ten numbers below one hundred, each with the same tens digit.

To exchange ten ones for one ten or one ten for ten ones in order to calculate more easily.

Add and subtract 1 to and from a 2-digit number crossing the tens boundary

Maths

In this unit pupils will add and subtract 1s and 10s from 2 digit numbers. They will use number facts to add/subtract a single-digit number to/from a 2-digit number. They will use a part-part-whole model to represent addition and subtraction. In the future unit pupils will learn to find 10 more or less than a 2-digit number They will  add and subtract 10 to/from a 2-digit number using number facts

In the prior unit pupils added 3 addends. They used strategies such as finding 2 addends to total 10 or 2 numbers to bridge though 10. In this unit pupils will add and subtract 1s and 10s from 2 digit numbers. They will use number facts to add/subtract a single-digit number to/from a 2-digit number. They will use a part-part-whole model to represent addition and subtraction.

Adding and subtracting ones and tens to and from 2-digit numbers

Which decade is missing on the number line?

Alex adds 1 one to these Base 10 blocks. Which picture shows the number he now has?

Alex taps one less than the number shown. What number does he tap?

Sam thinks of two numbers with a difference of 1      One of her numbers is 30      What could the other number be?

Which equation represents the relationship between the numbers on the number line.

Which of the following two numbers have a difference of 1? 

Sam gathers Base 10 blocks to show one more than 47     Which image shows his Base 10 blocks?

Which number completes the stem sentences? 58 is equal to {{ }} plus 1 and {{ }} plus 1 is equal to 58

Choose which equation represents this part-part-whole model, then solve it.

Alex represents this number. Which place value chart represents the number that is one less?

Solve each equation by matching correctly.

This lesson will soon be taken down.

Add and subtract 1 to and from a 2-digit number crossing the tens boundary

Lesson outcome