Math lesson plan · 8th grade (Year 9 in England) · 45 minutes
Graphs of linear equations y = mx + b
Algebra
CCSS 8.EE.B.6CCSS 8.F.A.3England: KS3 AlgebraEngland: GCSE Foundation Algebra
Objective and success criteria
Students will: Graphs of linear equations y = mx + b.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Slope (gradient) of a line; Evaluate expressions
Leads to: Find the equation of a line; Systems of linear equations (simultaneous equations); Functions: definition and comparison
Materials: Balance scales or a balance drawing, Algebra tiles, Function machine cards, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Slope (gradient) of a line; Evaluate expressions). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Find the value of 7x + 5 when x = 2. → 19Prompt: Replace x with 2.
- Find the value of 6x − 5 when x = 7. → 37Prompt: Replace x with 7.
- Find the value of 3x + 11 when x = 6. → 29Prompt: Replace x with 6.
Hook · 5 min
- Show a "think of a number" puzzle and ask the class to work out the starting number.
- Share the objective: Graphs of linear equations y = mx + b. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: Does the point (5, 11) lie on the line y = 3x − 4?
- Step 1: y = 3 × 5 − 4 = 11
- Step 2: It matches, so yes.
- Answer: Yes
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- Does the point (−3, −7) lie on the line y = 2x − 3? (Yes / No) → NoPrompt: Substitute the x-value into the equation.
- Does the point (2, 9) lie on the line y = 4x + 2? (Yes / No) → NoPrompt: Substitute the x-value into the equation.
You do: independent practice · 10 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Does the point (5, −9) lie on the line y = −3x + 6? (Yes / No) → YesPrompt: Substitute the x-value into the equation.
- Does the point (5, 16) lie on the line y = 2x + 6? (Yes / No) → YesPrompt: Substitute the x-value into the equation.
Watch out for
- Doing an operation to one side of an equation but not the other.
- Reading 3x as 3 + x, or thinking x always stands for one particular number.
Support and stretch
Support
- Review first: Slope (gradient) of a line.
- Use concrete materials: balance scales or a balance drawing.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Move on to: Find the equation of a line; Systems of linear equations (simultaneous equations); Functions: definition and comparison.
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-8.
Free lesson plan from eurekami.com/lesson-plan-builder