Math lesson plan · 7th grade (Year 8 in England) · 45 minutes
Collect like terms with negative coefficients
Algebra
CCSS 7.EE.A.1England: KS3 AlgebraEngland: GCSE Foundation Algebra
Objective and success criteria
Students will: Collect like terms with negative coefficients.
- 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: Simplify expressions: like terms; Add integers using sign rules
Leads to: Expand two brackets and simplify
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 (Simplify expressions: like terms; Add integers using sign rules). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Simplify 8x + 4x. → 12xPrompt: These are like terms: they both have x.
- −20 + (−19) = ? → -39Prompt: Same signs: add the sizes and keep the sign.
- Simplify 6x + 5 − x + 2. → 5x+7Prompt: Group the x terms together and the numbers together.
Hook · 5 min
- Show a "think of a number" puzzle and ask the class to work out the starting number.
- Share the objective: Collect like terms with negative coefficients. 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 −3x − 6 − 7x + 8.
- Step 1: (−3 + (−7))x + (−6 + 8)
- Step 2: −10x + 2
- Answer: -10x+2
- 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 −2x − 12 − 2x + 8. → -4x-4Prompt: Group the x-terms and the number terms.
- Simplify −5a − 4b + a − 4b. → -4a-8bPrompt: a-terms and b-terms are different kinds of term.
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 −3x − 4 − x + 12. → -4x+8Prompt: Group the x-terms and the number terms.
- Felix simplifies 5x − 8x + 1 and writes 13x + 1. What is the correct simplified expression? → -3x+1Prompt: The 8x term is being subtracted.
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: Simplify expressions: like terms.
- 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: Expand two brackets and simplify.
- 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-7.
Free lesson plan from eurekami.com/lesson-plan-builder