Uvero — STEM Learning

Choosing and Reading Bar-Graph Scales

A graph scale must use equal intervals and cover the data without distortion. Read the labelled axis and determine the value of one grid interval before reading a bar. A careful solution names the quantities, keeps place value or units visible, and explains why each operation fits.

Worked reasoning

A 10-unit change covers 5 spaces.
$10\div5=2$ units per space.

On a bar graph, labelled marks 0, 10 and 20 are each 5 grid spaces apart. What does one grid space represent?

Which statement best captures the central mathematical idea in Choosing and Reading Bar-Graph Scales?

Read the labelled axis and determine the value of one grid interval before reading a bar.

A familiar-looking calculation may be used without checking place value, units, conditions or what the answer represents.

A memorised formula is valid even when its conditions are not met.

The diagram or notation replaces the need to justify each mathematical step.

When starting a problem about Choosing and Reading Bar-Graph Scales, which move is most reliable?

Represent the given information clearly and identify the operation or relationship required for choosing and reading bar-graph scales.

Round every value before identifying the mathematical structure.

Choose the longest available formula and substitute immediately.

Assume the desired conclusion and work backwards without checking equivalence.

Which statement is a misconception that must be rejected when working with Choosing and Reading Bar-Graph Scales?

A familiar-looking calculation may be used without checking place value, units, conditions or what the answer represents.

Read the labelled axis and determine the value of one grid interval before reading a bar.

Represent the given information clearly and identify the operation or relationship required for choosing and reading bar-graph scales.

Estimate first, then reverse the operation or use a second representation to check that the answer is reasonable.