I like this hands-on approach to maths; great for those outdoor learners ~ this link opens up to an article on Kindergarten Math but so many of the activities can be adapted to younger children, like the leaf activity pictured here.
Metric Measurement Worksheets - Length Kindergarten, Grade One, Grade Two
Measure a friend! Work out how many cm tall they are, their arm length, leg length, foot length, hand span and around their head. A great metric measurement worksheet for teaching Centimeters/ Centimetres!