In grade 2 students move to using standard units to measure linear distances. Many classes move right to using standard rulers for this, without helping students understand some of the key concepts. Most of the issues students have are due to the fact they don’t really understand what rulers are, or how they work.
I feel one of the key principles in measurement is that students should not use a tool unless they have constructed one themselves. For linear measurement, this is what I would consider is an essential pathway:
|Students measure objects using centicubes|
|Students measure objects using centicube ruler|
|Students measure objects using standard ruler|
Most of the resources below support these transitions.