Teaching and Group Activities for Understanding
Day 1 Teaching
Revise place value, quizzing children about the digits in 4.03. Find 4.03 + 0.7. Rehearse writing 2-place decimal numbers. Use place value additions to emphasise the value of each digit, e.g. start with 4.56, add one hundredth, then add two tenths, subtract one whole, subtract four hundredths, subtract four tenths. Ask children to show you the new number each time.
Use the in-depth problem-solving investigation ‘Spiralling Decimals’ from NRICH as today’s group activity.
Or, use these activities:
-- Use place value to add and subtract numbers with two decimal places, one calculation at a time or in longer chains.
Day 2 Teaching
Use the place value grid on the ITP Moving digits to show the effect of multiplying and dividing by 10, 100 and 1000. The digits move to the left when multiplying and to the right when dividing. Emphasise that the decimal point does not move.
-- Explore decimal place value and number order when multiplying and dividing by 10, 100 and 1000.
Day 3 Teaching
Show children a counting stick. Say that one end represents 2; the other 3. Use this to demonstrate that we can round 1-place decimals to the nearest whole number, e.g. we round 2.4 to 2 and 2.7 to 3. Write some 2-place decimals between 2.3 and 2.4 and round these to the nearest tenth, then to the nearest whole number. Probe understanding of rounding: Write a number less than 6 with two decimal places that rounds up to 6, etc.
-- Explore rounding 2-place decimals marked on number lines, or while playing Bingo.