Free Grade 3 Introducing Inverse Matrices Lesson Plans
Free Grade 3 lesson plans for Introducing Inverse Matrices: 12 real questions with a full answer key and worked solutions. A matrix is a grid of numbers. For a 2×2 matrix [[a, b], [c, d]], the determinant is ad − bc.
Free
Foundation
25 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- RememberIdentify introducing inverse matrices
Identify introducing inverse matrices accurately in a familiar context.
Assessed by: Exit ticket of four short items
- UnderstandExplain introducing inverse matrices
Explain introducing inverse matrices accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate introducing inverse matrices
Calculate introducing inverse matrices accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare introducing inverse matrices
Compare introducing inverse matrices accurately in a familiar context.
Assessed by: Exit ticket of four short items
Prerequisites
Close these gaps first — each has its own free lesson, worksheet and quiz.
How Introducing Inverse Matrices works
A matrix is a grid of numbers. For a 2×2 matrix [[a, b], [c, d]], the determinant is ad − bc.
12 practice questions
Easy to hard, 24 marks in total. Try them first, then open the answers.
- 1.Find the determinant of [[-1, 2], [-4, -2]].[1]
- 2.Find the determinant of [[6, 6], [-1, -1]].[1]
- 3.Find the determinant of [[2, 4], [-4, 6]].[1]
- 4.Find the determinant of [[3, -2], [0, -1]].[1]
- 5.Find the determinant of [[0, 2], [-3, 4]].[2]
- 6.Find the determinant of [[-2, 2], [-1, -4]].[2]
- 7.Find the determinant of [[-4, 4], [5, 4]].[2]
- 8.Find the determinant of [[-2, 3], [-1, 6]].[2]
- 9.Find the determinant of [[5, -2], [-2, 6]].[3]
- 10.Find the determinant of [[4, 3], [6, 1]].[3]
- 11.Find the determinant of [[4, -4], [6, -2]].[3]
- 12.Find the determinant of [[0, -2], [1, -3]].[3]
Show answers and working
1. 10
det = ad − bc. -1 × -2 − 2 × -4 = 10.
2. 0
det = ad − bc. 6 × -1 − 6 × -1 = 0.
3. 28
det = ad − bc. 2 × 6 − 4 × -4 = 28.
4. -3
det = ad − bc. 3 × -1 − -2 × 0 = -3.
5. 6
det = ad − bc. 0 × 4 − 2 × -3 = 6.
6. 10
det = ad − bc. -2 × -4 − 2 × -1 = 10.
7. -36
det = ad − bc. -4 × 4 − 4 × 5 = -36.
8. -9
det = ad − bc. -2 × 6 − 3 × -1 = -9.
9. 26
det = ad − bc. 5 × 6 − -2 × -2 = 26.
10. -14
det = ad − bc. 4 × 1 − 3 × 6 = -14.
11. 16
det = ad − bc. 4 × -2 − -4 × 6 = 16.
12. 2
det = ad − bc. 0 × -3 − -2 × 1 = 2.
Worked examples
Find the determinant of [[4, 3], [-3, 2]].
- det = ad − bc.
- 4 × 2 − 3 × -3 = 17.
- Answer: 17
Find the determinant of [[5, 4], [6, 5]].
- det = ad − bc.
- 5 × 5 − 4 × 6 = 1.
- Answer: 1
Find the determinant of [[-4, 1], [-4, 1]].
- det = ad − bc.
- -4 × 1 − 1 × -4 = 0.
- Answer: 0
Interactive practice
Free, no account required — answer on screen or print it.
Common mistakes
What learners typically get wrong, and how to fix it.
Calculates ab − cd.
Correction: Multiply the diagonals: ad − bc.
Gets signs wrong with negatives.
Correction: Bracket negatives before multiplying.
Teacher tips
- · Colour the two diagonals in different colours.
Parent tips
- · Point out spreadsheets as grids of numbers.
Real-life applications
- · Computer graphics, transformations.
Assessment objectives
How mastery is evidenced, and which standards it maps to.
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Frequently asked
- Is this Grade 3 Introducing Inverse Matrices lesson plan really free?
- Yes. Every lesson plans on FreeMathWorksheet is free to use, print and share — no account, no paywall and no watermark.
- What should a learner already know before this?
- Start with Determinants. Each one has its own free lesson, worksheet and quiz.
- How is the lesson plan sequenced?
- Recognition first, then understanding, application, reasoning and finally mastery — the same ladder used across every free resource on the platform.
- What comes next after Introducing Inverse Matrices?
- Move on to Working with Inverse Matrices, Inverse Matrices in Context, Matrix Addition, Matrix Multiplication, which build directly on this idea.
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