Step 8

Examples of what pupils should know and be able to do

• Secondary mathematics exemplification: Understand and use decimal notation and place value; multiply and divide integers and decimals by powers of 10

Probing questions

• Give me some examples of numbers that you find easy to convert to standard form.
• Give me some examples of numbers that are hard to convert.
• What makes them hard?
• What strategies do you use?
• Where might you meet numbers written in standard form?
• When is standard form useful?

What if pupils find this a barrier?

Revisit work on multiplying and dividing decimals by 0.01, 0.1, 10, 100 and 1000 (Step 4 and Step 6).

Explore how very large and very small numbers are shown on scientific calculators.

Practise entering and interpreting numbers in standard form on a scientific calculator.

Examples of what pupils should know and be able to do

Know when to insert zeros as placeholders to indicate the degree of significance of the number. For example, 1.4007 is 1.40 to three significant figures.

Use numbers rounded to a given number of significant figures to work out an approximate answer.

• Secondary mathematics exemplification: Understand and use decimal notation and place value; multiply and divide integers and decimals by powers of 10

Probing questions

• Why do we need significant figures for rounding?
• Why do we use significant figures for rounding?
• How do we know which figures are significant?
• How do we know if figures are significant?

What if pupils find this a barrier?

Use sorting activities to help pupils explore the connections between decimal places and significant figures. See Teaching mental mathematics: Rounding.