Subtraction of positive and negative integers
Lesson details
Learning outcome
I can use the mathematical structures that underpin subtraction to add and subtract positive and negative integers.
Key learning points
- Any subtraction can be re-written as an equivalent addition.
- Subtracting a postive number is the same as adding a negative number.
- Subtracting a negative number is the same as adding a positive number.
Keywords
Additive inverse - The additive inverse of a number is a number that, when added to the original number, gives the sum of 0.
Absolute value - The absolute value of a number is its distance from zero. E.g. 5 and (−5) are both 5 away from zero and so both have an absolute value of 5.
Common misconception
Minus and a minus make a plus, 2 negatives make a positive, double negative makes a positive, etc.
The use of additive inverses should avoid this common misconception. Be aware that pupils maybe already be familiar with this statement.
Teacher tip
The introduction to rewriting a subtraction as an equivalent addition requires correct use of mathematical language. Watching the video of the teacher explanation could help.
Licence
Lesson video
Loading...
Prior knowledge starter quiz
6 Questions
Q1.Complete the statement. The value of a number is its distance away from zero.
Q2.Which integer does this set of counters represent?
Q3.Work out: 9 + (-7) =
Q4.Work out (-5) + (-3)
Q5.Starting with the calculation with the lowest answer, sort these calculations in order of size from lowest answer to highest answer.
Q6.Work out: 10 + (-12) + 7 + (-6) =
Assessment exit quiz
6 Questions
Q1.Complete the statement. The additive inverse of a number is a number that, when added to the original number, gives the sum of .
Q2.Match together each of these subtractions with its equivalent addition.
6 + (-4)
4 + (-6)
6 + 4
(-4) + (-6)
Q3.Match each calculation to its answer.
2
(-2)
10
(-10)
Q4.Work out (-5) - (-8)
Q5.Work out: (-1) + 2 - (-3) - 4 + (-5) =
Q6.Complete the statement. The missing integer is
To help you plan your 7 maths lesson on: Subtraction of positive and negative integers, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 7 maths lesson on: Subtraction of positive and negative integers, 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 3 maths lessons from the Arithmetic procedures with integers and decimals unit, dive into the full secondary maths curriculum, or learn more about lesson planning.