Math lesson plan · 4th grade (Year 5 in England) · 45 minutes
Solve equations with a letter for the unknown
Algebra
CCSS 4.OA.A.2CCSS 4.OA.A.3England: Y6 Algebra
Objective and success criteria
Students will: Solve equations with a letter for the unknown.
- 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: Find the unknown in multiplication and division equations; Add and subtract multi-digit numbers
Leads to: Use simple formulas written in words and letters; Puzzles with two unknowns
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 (Find the unknown in multiplication and division equations; Add and subtract multi-digit numbers). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- What number does ▢ stand for? 40 ÷ ▢ = 10 → 4Prompt: Read the equation as a sentence: what times or divided by what?
- 309 209 + 94 446 = ? → 403655Prompt: Line up the place values and add from the right.
- Mateo thinks of a number and multiplies it by 3. The answer is 9. What was the number? → 3Prompt: Write it as ▢ × 3 = 9.
Hook · 5 min
- Show a "think of a number" puzzle and ask the class to work out the starting number.
- Share the objective: Solve equations with a letter for the unknown. 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: Find n: n ÷ 7 = 3
- Step 1: 21 ÷ 7 = 3
- Step 2: n = 21
- Answer: 21
- 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.
- Find n: 12 × n = 108 → 9Prompt: Use the inverse operation.
- Daniel buys 9 identical T-shirts and pays $135. Write it as 9 × t = 135. What is t, the price of one T-shirt? → 15Prompt: What times 9 makes 135?
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.
- Find n: n ÷ 4 = 7 → 28Prompt: Use the inverse operation.
- Lucia buys 6 identical T-shirts and pays $90. Write it as 6 × t = 90. What is t, the price of one T-shirt? → 15Prompt: What times 6 makes 90?
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: Find the unknown in multiplication and division equations.
- 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: Use simple formulas written in words and letters; Puzzles with two unknowns.
- 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-4.
Free lesson plan from eurekami.com/lesson-plan-builder