Cross the hundreds boundary when adding and subtracting any 2-digit multiple of 10
Lesson details
Learning outcome
I can cross the 100s boundary when adding and subtracting multiples of ten.
Key learning points
- When you add and subtract multiples of 10, the ones digit stays the same.
- When you add and subtract multiples of 10, the tens digit and sometimes the 100s digit will change.
- Number facts can help when adding and subtracting multiples of 10
Keywords
Multiple - The result of multiplying a number by another whole number.
100s boundary - The point at which the numbers change into 100s numbers, or from one set of hundreds to another.
Common misconception
Pupils may have difficultly partitioning 10s when crossing the 100s boundary. (e.g. 125 - 40)
Pupils practice adding to/subtracting from multiples of 10 (e.g. 130 - 50) before exploring non-multiples of 10 (e.g. 85 + 30)
Teacher tip
Many pupils will find base ten blocks an essential resource for this lesson. Pupils should also be encouraged to use number lines to represent the problems, as they support children's thinking when crossing the hundreds boundary.
Licence
Lesson video
Loading...
Prior knowledge starter quiz
6 Questions
Q1.Which number pairs have a total of 10?
Q2.What is 40 + 10?
Q3.What is 20 + 20?
Q4.What is 10 less than 103?
Q5.Match up the equations to the answers.
115
125
105
135
Q6.Ping has a mass of 94 kg. Polly is 10 kg heavier. What is Polly's mass in kg?
Assessment exit quiz
6 Questions
Q1.Which numbers are multiples of 10?
Q2.Which calculations cross the 100s boundary?
Q3.What is 90 + 20?
Q4.What is 116 − 10?
Q5.Penny is 95 cm tall. She puts on a green hat which is 30 cm tall. What is the total height of Penny and her hat?
Q6.Piper and her blue hat have a total height of 107 cm. If her hat is 40 cm tall, how tall is Piper in cm?
To help you plan your 3 maths lesson on: Cross the hundreds boundary when adding and subtracting any 2-digit multiple of 10, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 3 maths lesson on: Cross the hundreds boundary when adding and subtracting any 2-digit multiple of 10, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 2 maths lessons from the Bridging 100: counting on and back in 10s, adding/subtracting multiples of 10 unit, dive into the full primary maths curriculum, or learn more about lesson planning.