Teaching and Group Activities for Understanding
Day 1 Teaching
Today we’re going to use two familiar resources that both represent or show numbers from 0.01 to 1 – the bead bar and the 100 square. Use tags to mark the tenths on a bead bar; count along in tenths, then hundredths. Show a blank 100 square with just 0.01, 0.02, and 0.03 marked. Discuss what number will be at the end of the top row/ in the square under that/ in the bottom right corner. Mark other numbers on the square. What size steps are we counting in going down the grid?
-- Use counting on and back in tenths or hundredths to fill in missing adjacent numbers in a 0.01–1 square.
-- Fill in a row and column of a 0.01–1 square; identify the numbers in ‘crosses’ drawn on the 0.01–1 square.
-- Work backwards to identify starting numbers when adding/subtracting tenths and hundredths.
Day 2 Teaching
Display the 0.01–1 square. Count in steps of 0.01 from 0.3 to 0.4, then back, then in steps of 0.1 from 0.05 to 0.95 and back. Write 0.35 + 0.4 and model, using the 0.01–1 square: start at 0.35, count on 0.4. Which digit changes? Repeat for 0.35 – 0.04 and 0.35 – 0.4.
Use the ‘Decimals in a row’ in-depth problem-solving investigation below as today’s group activity.
Or, use these activities:
-- Play a game adding and subtracting hundredths on a completed or blank 0.01–1 square.
Day 3 Teaching
Write: A snail has crawled 2.34m. It crawls 4cm more. How far has it crawled now? What calculation do we need to do? Which digit will change when we add 4cm? Why? Establish that 4cm is the same as 4/100 of a metre or 0.04m. Write the number sentence: 2.34m + 4cm = 2.38cm. Repeat with another word problem to add a multiple of 10cm.
-- Convert distances in m to cm, or vice versa, to help solve measures problems.
-- Solving measurement problems, recognise which digit will change when a number of m or cm is added.