Math lesson plan · 8th grade (Year 9 in England) · 45 minutes
Divide powers with the same base
Algebra
CCSS 8.EE.A.1England: KS3 NumberEngland: GCSE Foundation Number
Objective and success criteria
Students will: Divide powers with the same base.
- 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: Multiply powers with the same base
Leads to: Zero and negative exponents
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 (Multiply powers with the same base). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 2⁵ × 2⁸ = 2ⁿ. What is n? → 13Prompt: Write it out: 5 lots of 2, then 8 more lots of 2.
- Simplify 3y³ × 6y³. (9y⁶ / 18y⁹ / 9y⁹ / 18y⁶) → 18y⁶Prompt: Multiply the numbers.
- Kwame says 2³ × 2⁴ = 4⁷. Work out the correct value of 2³ × 2⁴ as a number. → 128Prompt: The base stays the same when you multiply powers.
Hook · 5 min
- Show a "think of a number" puzzle and ask the class to work out the starting number.
- Share the objective: Divide powers with the same base. 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: 6⁹ ÷ 6⁸ = 6ᵏ. What is k?
- Step 1: 9 − 8 = 1
- Step 2: 6¹
- Answer: 1
- 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.
- 8¹⁰ ÷ 8⁷ = 8ᵏ. What is k? → 3Prompt: Dividing cancels factors of the base.
- Simplify 30x⁹ ÷ 6x³. (5x⁶ / 5x³ / 5x¹² / 24x⁶) → 5x⁶Prompt: Divide the numbers.
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.
- Simplify 10x⁸ ÷ 5x². (2x¹⁰ / 2x⁴ / 5x⁶ / 2x⁶) → 2x⁶Prompt: Divide the numbers.
- Work out 3⁷ ÷ 3⁵ as a number. → 9Prompt: Use the rule first: subtract the exponents.
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: Multiply powers with the same base.
- 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: Zero and negative exponents.
- 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