Math lesson plan · 2nd grade (Year 3 in England) · 45 minutes
Story problems: work out the starting amount
Addition and subtraction
CCSS 2.OA.A.1England: Y2 Addition and subtractionEngland: Y3 Addition and subtraction
Objective and success criteria
Students will: Story problems: work out the starting amount.
- 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: Story problems: find the missing change; Find the missing number in additions and subtractions to 100
Leads to: the next skill in this area.
Materials: Base-ten blocks, Number lines, Hundred square, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Story problems: find the missing change; Find the missing number in additions and subtractions to 100). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Arjun had 8 marbles. Kai gave Arjun some more. Now Arjun has 15. How many marbles did Kai give? → 7Prompt: 8 + ? = 15
- Ben had 20 birds. Ben gave some to Isla. Now Ben has 4 left. How many birds did Ben give away? → 16Prompt: Ben started with 20 and ended with 4.
- Kwame had some books. Then Kwame got 5 more. Now Kwame has 8. How many books did Kwame have at the start? → 3Prompt: ? + 5 = 8
Hook · 5 min
- Give a real shopping total or a score difference and ask for a quick estimate first.
- Share the objective: Story problems: work out the starting amount. 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: Noah had some photos. Then Noah got 12 more. Now Noah has 38. How many photos did Noah have at the start?
- Step 1: 38 − 12 = 26
- Step 2: 26
- Answer: 26
- 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.
- Amara had some stones. Then Amara got 12 more. Now Amara has 29. How many stones did Amara have at the start? → 17Prompt: ? + 12 = 29
- Elena had some beads. Elena gave 20 to Ravi and has 37 left. How many beads did Elena have at the start? → 57Prompt: ? − 20 = 37
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.
- Isla had some stones. Isla gave 26 to Tariq and has 36 left. How many stones did Isla have at the start? → 62Prompt: ? − 26 = 36
- Mateo had 22 books. Ben gave Mateo some more. Now Mateo has 49. How many books did Ben give? → 27Prompt: 22 + ? = 49
Watch out for
- Subtracting the smaller digit from the bigger one in every column (52 − 17 = 45).
- Forgetting to add the regrouped (carried) ten.
Support and stretch
Support
- Review first: Story problems: find the missing change.
- Use concrete materials: base-ten blocks.
- 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-2.
Free lesson plan from eurekami.com/lesson-plan-builder