Step 8 Objective

Why do we use significant figures for rounding?

How do we know which figures are significant?

How do we know if figures are significant?

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.

Probing questions

Why do we need significant figures for rounding?

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 from level 5: number page 18.