Short Blocks

# Maths Year 4 Summer Addition & Subtraction (B)

Each unit has everything you need to teach a set of related skills and concepts.

## Appropriate strategies to add/subtract(suggested as 2 days)

### Planning and Activities

Day 1 Teaching
Everest is the highest mountain in the world at 8848m above sea level. Display table of heights to descend from the summit to base camp (see resources). Use column subtraction to subtract 453m from 8848m to find the height of ‘The balcony’ (1 move). Stress aligning the digits to the right. Repeat for 8848 – 952 (two moves: 100s & 10s), then 8848 – 985 (two moves: 100s & 1s).
Group Activities
-- Use counting up (Frog) to find height differences between camps on Everest.
-- Use compact subtraction to calculate the heights of each camp on Everest; check each subtraction using addition.

Day 2 Teaching
Write 3000 – 2674 on the board. Model compact column subtraction to find the answer (make quite an ordeal of it!). What might be a more efficient way to do this subtraction? Draw out using Frog. Draft a line from 2674 to 3000 and use Frog to solve. MUCH quicker! Write 4002 – 3978. Discuss an appropriate strategy. Choose strategies for other subtractions, e.g. 5324 – 5297, 6542 – 4362, 9874 – 2344, 6000 – 5873, 4012 – 3679, 6124 – 5968.
Group Activities
Use the ‘Subtraction trios’ in-depth problem-solving investigation below as today’s group activity.
Or, use these activities:
-- Make and justify choice of Frog or column subtraction to find differences.
-- Make and justify choice of Frog, counting back or column subtraction to find differences.

### You Will Need

• Table of ‘Heights to descend from Everest summit to base camp’ (see resources)
• Mini-whiteboards and pens
• ‘Table of heights of camps on Everest’ (see resources)
• Flipchart and pens
• ‘Mixed subtractions’ (see resources)
• Three sheets of paper
• ITP: Number Grid

### Mental/Oral Maths Starters

Suggested for Day 1
7 times table (simmering skills)

Day 2
Complements to 100 (pre-requisite skills)

### Worksheets

Day 1
Use Frog to subtract 4-digit numbers mainly either side of a multiple of 100.
Use column subtraction to subtract 3-digit from 4-digit numbers.

Day 2
Choose Frog or column subtraction to subtract pairs of 4-digit numbers.

### Mastery: Reasoning and Problem-Solving

• Write the missing numbers:
☐ + 886 = 1532
5875 + ☐ = 6293
9381 – 5864 = ☐
1001 – ☐ = 784
• True or false? Explain your ideas…
-- Subtracting from a multiple of 1000, it is best to use Frog.
-- Subtracting a 3-digit number from a 4-digit number always gives an answer greater than 1000.
-- Subtracting 4827 from 7284 will only involve moving amounts from 1 column.
-- Subtracting 895 from 2222, column subtraction is not the best method.

In-depth Investigation: Subtraction Trios
Children look for patterns in answers when subtracting 3-digit numbers from 4-digit numbers with consecutive digits.

### Extra Support

Frog's Epic Jumps
Subtracting numbers either side of a gap of 100, e.g. 502 – 396, 524 – 397 and 503 – 375