### Teaching and Group Activities for Understanding

**Day 1 Teaching**

Write 346 + 50. Which digit will change? Confirm it is just the 10s digit; model counting on in 10s from 346 to answer. Repeat with 231 + 30 and 636 + 20.

Write 376 + 50: Which digit will change? Count on in 10s to show how both 100s & 10s digits change. Repeat for 346 + 500, 336 – 50 and 846 – 500.**Group Activities**

-- Solve addition or subtraction word problems by counting on or back in 1s, 10s or 100s; cross multiples of 10 and 100.

-- Make up calculations that result in the 10s and/or the 100s digit changing.

**Day 2 Teaching**

Show a grid from 301 to 400. Demonstrate adding or subtracting 10s by moving up or down the grid. What happens when we add a ‘nearly number’ like 39 instead of 40? We need to add 40, then adjust by subtracting 1. Repeat for adding and subtracting other nearly numbers, e.g. 356 + 41, 356 + 39, 356 – 39, 382 – 59, 338 + 29.**Group Activities**

-- Add and subtract near multiples to 3-digit numbers with the same 1s digit.

**Day 3 Teaching**

Display ‘Word problems’ one at a time; ask children to work on them in pairs. Think carefully about the maths that is needed – write a number sentence; then answer the question. Discuss their thoughts and clarify any misunderstandings as you work through each question. Choose one of the following to create a new word problem: 268 + 30, 583 – 40, 355 + 200, 632 – 400, 346 + 19, 475 – 21.**Group Activities**

Use the in-depth problem-solving investigation ‘Place value puzzles’ as today’s group activity.

Or, use these activities:

-- Solve word problems by adding or subtracting multiples, or near multiples, of 10 and 100.

-- Use spinners to create word problems involving adding or subtracting multiples, or near multiples, of 10 and 100.