Math lesson plan · 5th grade (Year 6 in England) · 30 minutes
Add and subtract decimals
Decimals and percentages
CCSS 5.NBT.B.7England: Y5 Fractions (including decimals)England: Y6 Fractions (including decimals)
Objective and success criteria
Students will: Add and subtract decimals.
- 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: Tenths and hundredths as decimals; Column addition and subtraction
Leads to: Multiply decimals; Add and subtract decimals with different numbers of places; Subtract a decimal from a whole number
Materials: Place value chart with tenths and hundredths, Hundred squares, Number lines, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 4 min
- Quick retrieval from earlier learning (Tenths and hundredths as decimals; Column addition and subtraction). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Use column addition: 3511 + 3612 → 7123Prompt: Line up the digits by place value, ones under ones.
- What is the value of the digit 3 in 3.37? → 0.3Prompt: Name the places: ones . tenths hundredths.
- Use column addition: 3430 + 3171 → 6601Prompt: Line up the digits by place value, ones under ones.
Hook · 3 min
- Show two prices or race times with decimals and ask which is bigger, then why.
- Share the objective: Add and subtract decimals. Read the success criteria together.
I do: model it · 7 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: 39.4 + 58.03 = ?
- Step 1: 39.40 + 58.03 = 97.43
- Answer: 97.43
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 6 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- 80.1 + 41.77 = ? → 121.87Prompt: Line up the decimal points.
- 12.15 − 2.1 = ? → 10.05Prompt: Line up the decimal points and fill gaps with zeros.
You do: independent practice · 7 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 6 questions are on the student sheet below, with answers in the key.
Exit ticket · 3 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- 27.2 + 78.15 = ? → 105.35Prompt: Line up the decimal points.
- 13.87 − 2.2 = ? → 11.67Prompt: Line up the decimal points and fill gaps with zeros.
Watch out for
- Thinking 0.45 is bigger than 0.5 because 45 is bigger than 5.
- Moving the digits the wrong way when multiplying or dividing by 10.
Support and stretch
Support
- Review first: Tenths and hundredths as decimals.
- Use concrete materials: place value chart with tenths and hundredths.
- 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: Multiply decimals; Add and subtract decimals with different numbers of places; Subtract a decimal from a whole number.
- 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-5.
Free lesson plan from eurekami.com/lesson-plan-builder