Short Blocks

Maths Year 2 Autumn More Addition and Subtraction (B)

Each unit has everything you need to teach a set of related skills and concepts. 'Teaching for Understanding' provides whole-class teaching and fully differentiated adult-led group activities. ‘Problem-solving and Reasoning’ develops these skills, and includes questions to enable you to assess mastery. Practice sheets ensure procedural fluency. Extra support activities enable targeted work with children who are well below ARE.

‘UNIT PLAN’ gives you a text version of all parts of the unit to use in your school planning documentation. ‘DOWNLOAD ALL FILES’ gives you that unit plan plus all of associated documents. These bulk downloads are added value for Hamilton Friends and School Subscribers.

Unit 1 Add/subtract multiples of 10 (suggested as 2 days)

Objectives

Add/subtract multiples of 10 to/from 2-digit numbers
Unit 3: ID# 2297

National Curriculum
Add/Sub (i) (iii) (v)

Hamilton Objectives
10. Add a 2-digit number and 10s.
11. Count back in 1s or 10s and use number facts to take away.
12.Recognise that addition and subtraction are inverse operations; use addition to check
subtractions.

Teaching and Group Activities for Understanding

Day 1 Teaching
Use Spider on the 1-100 grid to demonstrate how we can add multiples of 10 to a 2-digit number, e.g. 46 + 30. Stress that Spider doesn’t have to count in 1s! Repeat, using Spider to subtract multiples of 10, e.g. 63 – 40.
Group Activities
-- Children play a game using Spider on the 1-100 grid to rehearse adding and subtracting multiples of 10.

Day 2 Teaching
Use a bead string to demonstrate how we can add multiples of 10 to a 2-digit number. Note that the 1s digit does not change. Repeat to show how we can subtract multiples of 10.
Group Activities
Use the in-depth problem-solving investigation ‘The Number Square!’ from NRICH as today’s group activity. Or, use these activities:
-- Children use a 100-beaded line to add or subtract 20, 30, 40 or 50. They choose their own calculations to solve.
-- Some children investigate patterns when adding and subtracting given multiples of 10 to 2-digit numbers.

You Will Need

  • 1-100 grids (see resources)
  • Small cubes
  • Plastic Spider
  • ‘Add or Subtract 10s’ cards (see resources)
  • ‘Spider counters’ (see resources)
  • Small circles of card
  • 0-100 bead strings
  • Large beaded number line
  • Additional activity sheets (see resources)

Mental/Oral Maths Starters

Day 1
Count on and back in 10s, with 100 grid (pre-requisite skills)

Day 2
Count on and back in 10s, using a bead bar (pre-requisite skills)

Procedural Fluency

Day 1
Children practise adding and subtracting multiples of 10 to/from 2-digit numbers using a 1-100 grid and Spider.

Day 2
Children use a beaded line to solve addition and subtraction calculations. Some will find the missing number in a number sentence.

Mastery: Reasoning and Problem-Solving

  • Complete this grid:
+20
54
6797
  • Explain what Bill has done wrong in his homework:
54+40=84
76-30=73
23+50=28
64-40=20
  • Choose a number to write in the first empty box:
    ☐ + 20 – 30 + 10 = ☐
    Do the calculation. Make an observation about the answer.
    Repeat with a different starting number.
    Explain what is happening.


In-depth Investigation: The Number Square!
Focus on strategies involving adding/subtracting multiples of 10 to put numbers back in the correct place on the 100-grid, e.g. 14 + 40 = 54, 87 - 60 = 27. The Number Square! from nrich.maths.org.

Extra Support

Spider's Workout
Adding and subtracting 10 using a 1-100 grid

Unit 2 Add/subtract 11, 12, 21, 22, etc (suggested as 3 days)

Objectives

Add/subtract 11, 12, 21, 22, etc. to/from 2-digit numbers
Unit 4: ID# 2311

National Curriculum
Add/Sub (i) (iii)

Hamilton Objectives
10. Add a 2-digit number and 10s; add two 2-digit numbers that total <100 by counting on in 10s and 1s.
11. Count back in 1s or 10s or use number facts to take away, e.g. 27-3 = or 54-20 =.
15. Solve problems involving addition and subtraction of numbers, quantities and measures, using recall of number facts and appropriate models and images.

Teaching and Group Activities for Understanding

Day 1 Teaching
Use the 1-100 grid to demonstrate how we can add 11, 12, 13, 21, 22 or 23 using Spider first and then adding the ones. Share plenty of examples, with children recording number sentences.
Group Activities
Use the ‘Count down to Zero’ in-depth problem-solving investigation below as today’s group activity.
Or, use these activities:
-- Create, describe and begin to explain patterns created by repeated addition of 11, 12, 13, 21, 22 and 23.

Day 2 Teaching
Children show 40 on bead strings. Add 12 by sliding 10 beads then 2 more. Record 40 + 12 = 52. Show how to record hops of 10 and 2 on a beaded line. Also show on a 1-100 grid. Which do children find easier? Repeat for adding 13, 21, 22, 23, 31, 32 and 33.
Group Activities
-- Play a game to practise adding 11, 12, 13, 21, 22, 23, 31, 32, and 33. Some children will reason about number choices.

Day 3 Teaching
Write 65 – 11. Ask children how to the find answer. Demonstrate jumping back on the beaded line and also moving up and across on the 1-100 grid. Repeat for other subtractions, e.g. 48 – 11 and 48 – 21.
Group Activities
-- Using a 1-100 grid, children play a game in pairs where they rehearse adding or subtracting near multiples of 10, beginning to predict and reason about their answers.

You Will Need

  • 1-100 grids (see resources)
  • Counters of different colours & coins
  • 0-100 beaded lines
  • Addition cards (see resources)
  • Additional activity sheets (see resources)
  • Coins, including lots of 10ps and 1ps
  • 1-100 bead strings
  • Biscuits

Mental/Oral Maths Starters

Day 1
Add/ subtract 20 (pre-requisite skills)

Suggested for Day 2
2 more/less than 2-digit numbers (simmering skills)

Suggested for Day 3
Add 3 to 2-digit numbers (simmering skills)

Procedural Fluency

Day 1
Most children create their own questions by selecting pairs of numbers to add. Some will complete a challenge involving missing numbers.

Day 2
Children are set different challenges to add 11, 12, 13, 21, 22, 23, 31, 32 or 33 to other 2-digit numbers; answers ≤110.

Day 3
Children calculate which of a set of given numbers is required to make a set of given calculations correct.

Mastery: Reasoning and Problem-Solving

  • Write the missing numbers in these calculations:
    56 + ☐ = 86
    86 + ☐ = 87
    So, 56 + ☐ = 87

    51 – ☐ = 31
    31 – ☐ = 29
    So, 51 – ☐ = 29
  • Complete these diagrams:
    Diagram 1:

?
4821

Diagram 2

63
31?
  • I think of a number, then add 11, then 22, then 33 to it. My answer is 70. What number did I start with?

In-depth Investigation: Count Down to Zero
Children take turns to subtract 1, 2 or 3 from a 2-digit number greater than 20. They use strategies to help them win a game by reaching zero first.

Extra Support

Down the Stairs
Adding 11 to 2-digit numbers

Up the Stairs
Subtracting 11 from 2-digit numbers

Unit 3 Add/subtract near multiples of 10 (suggested as 3 days)

Objectives

Add near multiples of 10 to/from 2-digit numbers
Unit 5: ID# 2333

National Curriculum
Num/PV (vi)
Add/Sub (i) (ii) (iii)

Hamilton Objectives
6. Use place value and number facts to solve problems, e.g. 60 - 40 = 20.
10. Add a 2-digit number and 10s; add two 2-digit numbers that total <100.
15. Solve problems involving addition and subtraction of numbers, using recall of number facts and appropriate models and images.

Teaching and Group Activities for Understanding

Day 1 Teaching
Write 36 + 19. 19 is nearly..? 20! Ring 36 on a 1-100 grid. Count on to 2 steps of 10 to work out 36 + 20. But 19 isn’t a multiple of 10 - it is only nearly 20, so we have to take off 1. Add other near multiples of 10 by adding a multiple of 10 and adjusting.
Group Activities
-- Children practise adding ‘nearly numbers’ by adding a multiple of 10 and then adjusting to find the answer. Children use a 1-100 grid to support addition and/or investigate patterns.

Day 2 Teaching
Display a 1-100 grid, with multiples of 10 coloured red. Identify numbers that are nearly multiples of 10 - ‘nearly numbers’ - 9, 19, 29 etc. 29 is nearly..? 30. Repeat for each ‘nearly number’. Use a calculator to add nearly numbers to 2-digit numbers. Notice patterns.
Group Activities
Use the ‘Nines to Zero’ in-depth problem-solving investigation below as today’s group activity.
Or, use these activities:
-- Whole class investigation. In order to focus on mathematical reasoning, children use calculators. Describe and explain patterns by recording the calculations and answers that occur when adding ‘nearly numbers’.

You Will Need

  • 1-100 grid with multiples of 10 squares coloured red (see resources)
  • 1-100 grids (see resources)
  • Nearly numbers board (see resources)
  • Small square Post-it notes
  • Calculators

Mental/Oral Maths Starters

Day 1
Count in 10s (pre-requisite skills)

Day 2
Add 20 (pre-requisite skills)

Procedural Fluency

Day 1
Children rehearse adding ‘nearly numbers’ using the strategy of adding the multiple of 10 and then subtracting 1.

Day 2
Children use calculators to help them look for patterns when adding 9, 19, 29 and 39.

Mastery: Reasoning and Problem-Solving

  • Write 3 additions which include a 2-digit number and the number 22.
  • Complete each number sentence:
    27 + ☐ = 46
    ☐ + 29 = 73
    ☐ – 19 = 56
  • Complete the patterns:
    17, 26, __, 44, __, __.
    5, 34, 63, __, __.
  • Start with 21. Add 9, then add 19, then add 29. What is the answer? Subtract 9, then subtract 19, then subtract 29.
  • Start with 18 and do the same 6 calculations. Can you predict the answer before doing the last 3 calculations?

In-depth investigation: Nines to Zero
Children repeatedly add 9 or 19 to numbers until they reach a multiple of 10. Look for patterns. Make and test predictions based on the patterns.

Unit 4 Add pairs of 2-digit numbers (suggested as 2 days)

Objectives

Add pairs of 2-digit numbers
Unit 6: ID# 2341

National Curriculum
Num/PV (vi)
Add/Sub (i) (ii) (iii)

Hamilton Objectives
6. Use place value and number facts to solve problems, e.g. 60 - 40 = 20.
10. Add a 2-digit number and 10s; add two 2-digit numbers that total <100.
15. Solve problems involving addition and subtraction of numbers, using recall of number facts and appropriate models and images.

Teaching and Group Activities for Understanding

Day 1 Teaching
Show 4 items priced 45p, 38p, 49p, 33p, & 4 different items priced 21, 22p 23p and 24p. Use these to find totals of pairs of prices, e.g. 49p and 22p, by adding the 10s and then the 1s.
Group Activities
-- Play games involving adding pairs of 2-digit numbers.

Day 2 Teaching
Ask children in 2s to make up 2 additions, 1 where they add a ‘nearly’ number and 1 where they add an ‘ordinary’ number. Share & ask children to help you work out answers either using a 1-100 grid or a 0-100 beaded line.
Group Activities
Use the in-depth problem-solving investigation ‘Five Steps to 50’ from NRICH as today’s group activity.
Or, use these activities:
-- Most children play Bingo to practise adding ‘ordinary’ and ‘nearly’ numbers, choosing and using appropriate strategies. Some may sort then solve calculations.

You Will Need

  • Four items priced 45p, 38p, 49p and 33p, & four priced 21, 22p 23p and 24p
  • 1-100 grid (see resources)
  • 0 to 100 beaded line to display on the board (see resources)
  • Additional activity sheets (see resources)

Mental/Oral Maths Starters

Day 1
Add 3 to 2-digit numbers (pre-requisite skills)

Suggested for Day 2
Number facts (simmering skills)

Procedural Fluency

Day 1
Most children use ‘Choose your own’ sheets to generate and solve different addition problems involving adding 2-digit numbers.

Day 2
Children practise adding ‘ordinary’ and ‘nearly’ numbers using a chosen method.

Mastery: Reasoning and Problem-Solving

  • Here are the prices for 5 pencils:
    A 34p
    B 29p
    C 45p
    D 52p
    E 19p
    The total is 53p. Which 2 pencils did you buy?
    What is the most you can spend on 2 pencils?
    What is the least you can spend on 2 pencils?
  • What’s the same, what’s different?
    54 + 39 = 93, 59 + 34 = 93
    39 + 54 = 93, 34 + 59 = 93


In-depth investigation: Five Steps to 50 (NRICH.maths.org)

Children navigate the number line by adding or subtracting 1, 10 or 100.

Extra Support

Sum Patterns
Using pattern and number bonds to work out related additions, e.g. 3 + 2 = 5, so 13 + 2 = 15, 23 + 2 = 25, 33 + 2 = 35