Measurement Length and Perimeter - Equivalent Lengths – mm & cm - Planning

In a Year 3 mathematics lesson, the concept of equivalent lengths in millimetres and centimetres is introduced. Pupils are encouraged to understand that 10mm is equivalent to 1cm and use this knowledge to convert measurements from one unit to the other. The lesson includes a variety of resources such as worksheets, presentations, rulers, and classroom objects to facilitate learning. Key vocabulary terms like 'length', 'centimetre', 'millimetre', 'convert', and 'equivalence' are highlighted to enhance understanding. The class begins with a recap of previous lessons, followed by activities that involve examining rulers to identify millimetre intervals, and using this information to count and convert lengths. Children work in pairs to measure classroom objects, ensuring they start at the zero mark on the ruler, and discuss which items are best measured in millimetres.

The lesson progresses with practical tasks where students measure objects, record their findings in both millimetres and centimetres, and explore part-whole relationships to partition measurements into different units. They are guided to develop fluency in converting between units using part-whole models and to articulate their reasoning with stem sentences like "If I know there are 10mm in 1cm then I know…". Independent learning is supported by differentiated worksheets, and the session concludes with a plenary to consolidate the day's learning. The lesson plan also caters to different levels of understanding, with activities ranging from using number lines with some millimetre markings to aid in visualising equivalent lengths, to using unmarked number lines for those working at greater depth.