How can we subtract numbers? - Lesson 2: Using number lines

They will tackle subtraction questions using a variety of different methods. They will also be challenged to use what they know about numbers to help them use partitioning and landmark numbers to solve problems. Over the course of the five lessons in this ‘How can we subtract numbers?’ Complete Series, children use objects, pictures, number lines, hundred squares and mental methods to solve number sentences.

The first lesson in this series focuses on using pictorial representations and objects to subtract up to two numbers from a total. Your children will begin by subtracting one number from a total to help out two pet shop owners. They will be encouraged to think about how they can partition the number to make solving the number sentence easier. Your class will begin to understand that how their objects or pictures are arranged and how they partition the number they are subtracting can make solving the problem much easier.

The second lesson in this series focuses on using number lines to subtract up to two numbers from a total. Your class will begin by discussing how they use a number line differently when finding the difference and subtracting by counting back. They will then begin subtracting by recording jumps on a number line. They will be encouraged to think about how they can partition the number to make solving the number sentence easier.

The third lesson in this series focuses on using bead strings to subtract multiples of ten from a number. Your class will begin by discussing the different ways they can use bead strings to solve subtraction problems. They will be encouraged to think about how they can partition ten to make solving the number sentence and bridging landmark numbers easier.

The penultimate lesson in this series focuses on using a hundred square to subtract multiples of ten and multiples of one from a number. Your class will begin by sharing what they notice about hundred squares and how the numbers are arranged in the rows and columns. They will be encouraged to think carefully about the direction they should be moving around the hundred square when subtracting.

The final lesson in this series gets your class using their knowledge of number facts as they solve subtraction problems mentally. They will choose the mental method that works best for them, be encouraged to explain what they did and then prove their answer is correct using a different method.