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.
- 7³ × 7⁸ = 7ⁿ. What is n? → 11Prompt: Write it out: 3 lots of 7, then 8 more lots of 7.
- Simplify 5a⁵ × 5a³. (25a¹⁵ / 10a⁸ / 10a¹⁵ / 25a⁸) → 25a⁸Prompt: Multiply the numbers.
- Diego says 2⁵ × 2³ = 4⁸. Work out the correct value of 2⁵ × 2³ as a number. → 256Prompt: 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.
- 9¹⁴ ÷ 9⁸ = 9ᵏ. What is k? → 6Prompt: Dividing cancels factors of the base.
- Simplify 24x¹¹ ÷ 6x⁶. (4x¹⁷ / 4x² / 4x⁵ / 18x⁵) → 4x⁵Prompt: 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.
- 3³ ÷ 3² = 3ᵏ. What is k? → 1Prompt: Dividing cancels factors of the base.
- Simplify 20x⁹ ÷ 4x⁴. (5x⁵ / 5x¹³ / 16x⁵ / 5x²) → 5x⁵Prompt: Divide the numbers.
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