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Level 5: Iterates the unit

Measuring length requires determining the number of unit lengths that fit end to end along an object, with no gaps or overlaps. When you have only one copy of the unit of length to be used, you need to be able to use a single unit repeatedly (iterating) to measure or construct length. The process of repeating a unit length end to end along an object is known as unit-length iteration. Students can gain an understanding of how a multi-unit ruler works by constructing one by iterating a single unit and quantifying the accumulated distance numerically.

Students also need to appreciate the quantitative relationship between length and the number and size of units used to measure length (i.e. if you halve the size of the units you will have twice as many units in the measure).

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Making a multi-unit ruler