Find 10 more or less than a 2-digit number.
Lesson details
Learning outcome
I can find 10 more or 10 less than a two-digit number.
Key learning points
- When finding 10 more or 10 less than any two-digit number, the ones digits does not change.
- When finding 10 more than a number below 100, the tens digit increases by one.
- When finding 10 less than a number below 100, the tens digit decreases by one.
Keywords
10 more - 10 more than is when there is a greater amount by 10 than another item in the set.
10 less - 10 less than is when there is a smaller value by 10
Increase - Make something bigger (in size or quantity).
Decrease - Make something smaller (in size or quantity).
Common misconception
Children may default to counting in ones to find ten more or ten less.
Use representations that highlight the structure of the base 10 system, e.g. Base 10 blocks/one hundred squares, and also 'dual counting' to support understanding of 'unitising', i.e. that using 'ten' as a unit can help to calculate more efficiently.
Teacher tip
Encourage children to seek and notice patterns and to articulate their thinking around these. Vary the language used, e.g. '45 is ten more than 35' and 'ten more than 35 is 45', so children do not think that the greater number always come after the smaller number when using 'ten more than'.
Licence
Lesson video
Loading...
Prior knowledge starter quiz
6 Questions
Q1.Which equation would be used to solve this problem? Sam collected 56 pebbles and Alex collected 8
How many pebbles did they collect altogether?
Q2.Sam and Alex collected 45 shells but Alex dropped some. Now, they have 37 shells. How many did Alex drop? shells.
Q3.Alex and Sam collected 34 pencils in class. Sam collected 7 pencils. How many did Alex collect? pencils.
Q4.Which of these equations can be solved by bridging a multiple of 10?
Q5.Which of these equations can be solved by bridging a multiple of 10?
Q6.Which of these known facts could help you to solve this equation? 66 + 7 = ___
Assessment exit quiz
6 Questions
Q1.Match the number of tens to the correct multiple of 10
40
20
90
50
100
Q2.Match to complete the sentence.
40
50
100
60
Q3.Match to complete the sentence.
the tens digit increases by one, but the ones digit remains the same.
the tens digit decreases by one, but the ones digit remains the same.
Q4.Match so that the second number is 10 more than the first.
27
33
56
75
Q5.What is the missing number below?
Q6.Look at the number in the place value chart. 10 less than this number is
To help you plan your 2 maths lesson on: Find 10 more or less than a 2-digit number., download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 2 maths lesson on: Find 10 more or less than a 2-digit number., 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 1 maths lessons from the Adding and subtracting ones and tens to and from 2-digit numbers unit, dive into the full primary maths curriculum, or learn more about lesson planning.