Math lesson plan · 9th grade (Year 10 in England) · 45 minutes
Divide monomials using exponent laws
Algebra
CCSS 8.EE.A.1England: GCSE Foundation Algebra
Objective and success criteria
Students will: Divide monomials using exponent laws.
- 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 monomials using exponent laws
Leads to: Take out the greatest common factor of a polynomial
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 monomials using exponent laws). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Simplify: (−x)(4x⁵) → -4x^6Prompt: Multiply the numbers.
- Simplify: (4x⁵y³)(−2xy) → -8x^6y^4Prompt: Deal with numbers, then each letter separately.
- x¹ × x⁻³ × x⁻⁴ = xᵏ. Find k. → -6Prompt: Multiplying powers of the same base: add the exponents.
Hook · 5 min
- Show a "think of a number" puzzle and ask the class to work out the starting number.
- Share the objective: Divide monomials using exponent laws. 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: Simplify: −16x³ ÷ 4x²
- Step 1: −16 ÷ 4 = −4
- Step 2: x³ ÷ x² = x
- Step 3: −4x
- Answer: -4x
- 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.
- Simplify: 24x⁸ ÷ 6x³ → 4x^5Prompt: Divide the numbers.
- 16x⁴ ÷ 4x⁷ = 4xᵏ. Find k. → -3Prompt: Subtract the exponent of the divisor from the exponent of the dividend.
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: (24x⁷y) ÷ (4x²y⁴). Negative exponents are fine. → 6*x^(5)*y^(-3)Prompt: Treat numbers, x and y separately.
- 9x ÷ 3x² = 3xᵏ. Find k. → -1Prompt: Subtract the exponent of the divisor from the exponent of the dividend.
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 monomials using exponent laws.
- 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: Take out the greatest common factor of a polynomial.
- 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-9.
Free lesson plan from eurekami.com/lesson-plan-builder