Solve problems by adding and subtracting to or from 3-digit numbers
Lesson details
Learning outcome
I can solve problems by adding to and subtracting from 3-digit numbers.
Key learning points
- Number lines can record the steps in our thinking when we are partitioning to add and subtract.
- The 1s digit does not change when you add or subtract a multiple of ten.
- Number facts to 10 help when crossing the 10s and 100s boundaries.
Keywords
Bridge - Bridging is a strategy which uses addition or subtraction to cross a number boundary.
Partition - Partition means splitting an object or value down into smaller parts.
100s boundary - The 100s boundary is the point at which the numbers change into 100s numbers, or from one set of hundreds to another.
Common misconception
Pupils may struggle to partition 10s numbers to help them bridge a 100s boundary.
Encourage pupils to calculate the number of tens needed to add or subtract to the 100s number, then add or subtract the remainder.
Teacher tip
Pupils will need to use number lines to represent their thinking. Base ten blocks may also be helpful for some pupils, although these do not feature in the lesson. They can be used alongside number lines to support pupil learning.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.How should you partition 5 to calculate 98 + 5?
Q2.Which calculations cross a 100s boundary?
Q3.What is 230 + 30?
Q4.270 − 40 =
Q5.Which calculation is shown by the number line representation?
Q6.Use the number line to find the missing number. 510 − ___ = 460
Assessment exit quiz
6 Questions
Q1.How should you partition 60 to calculate 160 + 60?
Q2.How should you partition 60 to calculate 210 − 60?
Q3.245 + 20 =
Q4.320 − 40 =
Q5.Colin the cat is 410 cm high in a tree. He climbs down 50 cm. How high is he now?
Q6.Katya is in a tree. She climbs down 30 cm. She is now 288 cm high. How high was she when she started? cm
To help you plan your 3 maths lesson on: Solve problems by adding and subtracting to or from 3-digit numbers, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 3 maths lesson on: Solve problems by adding and subtracting to or from 3-digit numbers, 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 Representing 3-digit numbers, comparing and positioning on number lines unit, dive into the full primary maths curriculum, or learn more about lesson planning.