Math lesson plan · 8th grade (Year 9 in England) · 45 minutes
Name and use angle pairs on parallel lines
Geometry
CCSS 8.G.A.5England: KS3 Geometry and measuresEngland: GCSE Foundation Geometry and measures
Objective and success criteria
Students will: Name and use angle pairs on parallel lines.
- 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: Angles with parallel lines
Leads to: Solve angle equations on parallel lines
Materials: Rulers and protractors, Squared or dotted paper, Shape cut-outs, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Angles with parallel lines). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- A line crosses two parallel lines. One angle is 128°. What is the co-interior (same-side interior) angle to it, in degrees? → 52Prompt: Alternate angles are equal (Z shape). Corresponding angles are equal (F shape).
- Alternate angles on parallel lines are (3x + 8)° and 77°. Find x. → x = 23Prompt: Alternate angles are equal.
- A line crosses two parallel lines. One angle is 123°. What is the co-interior (same-side interior) angle to it, in degrees? → 57Prompt: Alternate angles are equal (Z shape). Corresponding angles are equal (F shape).
Hook · 5 min
- Show a photo of a building, a tile pattern or a road sign and ask what shapes and angles students can spot.
- Share the objective: Name and use angle pairs on parallel lines. 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: A transversal crosses two parallel lines. Two angles are in the same position at each crossing. What are they called?
- Step 1: They are corresponding angles.
- Answer: corresponding
- 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.
- A transversal crosses two parallel lines. Two angles are outside the parallel lines, on opposite sides of the transversal. What are they called? (corresponding / alternate exterior / alternate interior / co-interior (same-side interior)) → alternate exteriorPrompt: Interior means between the parallel lines; exterior means outside them.
- Two parallel lines are cut by a transversal. One angle is 105°. What is its corresponding partner? → 105Prompt: Corresponding and alternate angles are equal.
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.
- Two parallel lines are cut by a transversal. One angle is 39°. What is its corresponding partner? → 39Prompt: Corresponding and alternate angles are equal.
- A transversal crosses two parallel lines. Two angles are in the same position at each crossing. What are they called? (corresponding / co-interior (same-side interior) / alternate exterior / alternate interior) → correspondingPrompt: Interior means between the parallel lines; exterior means outside them.
Watch out for
- Thinking a square turned on its corner is no longer a square.
- Reading the wrong scale on a protractor.
Support and stretch
Support
- Review first: Angles with parallel lines.
- Use concrete materials: rulers and protractors.
- 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: Solve angle equations on parallel lines.
- 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