Math lesson plan · 5th grade (Year 6 in England) · 45 minutes
Decimal addition and subtraction in real life
Decimals and percentages
CCSS 5.NBT.B.7England: Y6 Fractions (including decimals)
Objective and success criteria
Students will: Decimal addition and subtraction in real life.
- 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: Add and subtract decimals with different numbers of places
Leads to: the next skill in this area.
Materials: Place value chart with tenths and hundredths, Hundred squares, Number lines, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Add and subtract decimals with different numbers of places). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 21.5 + 8.199 = ? → 29.699Prompt: Line up the decimal points, not the last digits.
- 2.54 − 1.7 = ? → 0.84Prompt: Write 1.7 as 1.70.
- Amara lined up the last digits to add 8.1 + 0.90 and got 1.71. What is the correct answer? → 9Prompt: Decimal points must line up.
Hook · 5 min
- Show two prices or race times with decimals and ask which is bigger, then why.
- Share the objective: Decimal addition and subtraction in real life. 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: Nia was 1.35 m tall last year and has grown 0.37 m. How tall is Nia now, in metres?
- Step 1: 1.35 + 0.37 = 1.72
- Answer: 1.72
- 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.
- Kofi was 1.31 m tall last year and has grown 0.33 m. How tall is Kofi now, in metres? → 1.64Prompt: Add the two lengths.
- A jug holds 3.3 litres of lemonade. 0.5 litres and then 1.4 litres are poured out. How much is left? → 1.4Prompt: Add the amounts poured out.
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.
- Diego was 1.75 m tall last year and has grown 0.26 m. How tall is Diego now, in metres? → 2.01Prompt: Add the two lengths.
- In a 100 m race Mei ran 11.41 s and Noah ran 11.39 s. What was the difference between their times, in seconds? → 0.02Prompt: Subtract the smaller time from the larger.
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: Add and subtract decimals with different numbers of places.
- 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
- 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