### Teaching and Group Activities for Understanding

**Day 1 Teaching**

Write 23 × 10 and 23 × 5 and show how we can use the former to solve the latter. Repeat for 23 × 20 and 23 × 19. Model 23 × 6 as 23 × 3 doubled. Discuss strategies for 23 × 8 and 123 × 8 by repeated doubling.

**Group Activities: T with Y5**

Y5/Y6 -- Explore mental methods based on doubling and halving to multiply by 5, 20, 6, 4 and 8.

**Day 2 Teaching**

Use 240 ÷ 10 to find 240 ÷ 5 and 240 ÷ 20. Use 270 ÷ 3 to find 270 ÷ 6. Use repeated halving to divide by 4 and 8.**Group Activities: T with Y6**

Use the in-depth problem-solving investigation for this unit ‘Get to the root’ as today’s group activity.

Or, use these activities:

Y5 -- Explore mental methods to divide by 5, 20 and 4. Some children will also divide by 6 and 8.

Y6 -- Explore mental methods to divide by 5, 20, 6, 4 and 8. Some children will divide 3-digit numbers by 5, 20 and 8 to give answers with decimal places.

**Day 3 Teaching**

Show a table of dimensions of scale models of dinosaurs. Each model is 1/20 of the actual height and length. Ask how we can calculate full size. Repeat for a shop that is selling toy dinosaurs where each measurement is 1/200 of the size of the real dinosaurs.

**Group Activities: T with Y5**

Y5 -- Calculate the heights of children and classroom furniture if heights are scaled up by a factor of 5. Some children will work with a factor of 8 and will scale widths by a factor of 4.

Y6 -- Scale down dimensions of dinosaurs by factors of 10 or 100 to sketch on paper. Look at relative sizes.

**Day 4 Teaching**

Describe how much a blue whale eats and the rates of growth of a calf. Define ‘rate’. Calculate the growth in one week.**Group Activities: T with Y6**

Y5 -- Calculate how long different creatures take to eat their body weight in food. Calculate a rate for tasks, and how many of these tasks could be performed in a school day at the same rate.

Y6 -- Solve and create problems involving rates in the natural world.