Math lesson plan · 5th grade (Year 6 in England) · 30 minutes
Add and subtract decimals with different numbers of places
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 with different numbers of places.
- 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
Leads to: Decimal addition and subtraction in real life; Multiply a decimal by 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 (Add and subtract decimals). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 9.3 + 6.37 = ? → 15.67Prompt: Line up the decimal points.
- 12.83 − 6.1 = ? → 6.73Prompt: Line up the decimal points and fill gaps with zeros.
- 29.2 + 84.07 = ? → 113.27Prompt: Line up the decimal points.
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 with different numbers of places. 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: 2.2 + 1.003 = ?
- Step 1: 2.200 + 1.003 = 3.203
- Answer: 3.203
- 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.
- 8.2 + 4.118 = ? → 12.318Prompt: Line up the decimal points, not the last digits.
- 3.45 − 2.6 = ? → 0.85Prompt: Write 2.6 as 2.60.
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.
- 2.93 − 1.4 = ? → 1.53Prompt: Write 1.4 as 1.40.
- Luis lined up the last digits to add 8.7 + 0.91 and got 1.78. What is the correct answer? → 9.61Prompt: Decimal points must line up.
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.
- 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: Decimal addition and subtraction in real life; Multiply a decimal by 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