Uncle Norm finds Alanna and Kevin in the Workshop, squinting through a magnifying glass at small maple trees. He wants to know when they can get sap: bean seeds can grow as high as the tool shed in one summer, so why not a baby tree? The Rads explain that we measure a bean’s growth in weeks and months, and Uncle Norm’s growth in years and decades, but trees grow more slowly: over decades, centuries, and sometimes even millennia. They visit a sugar bush to find out more.

The Gist: A measurement always has units. For example, we measure time in millennia, centuries, decades, years, days, weeks, and hours. Without the unit, we do not know how much time has passed. The units that go with our measurements tell us what we are measuring and how much we have. In the curriculum, children are required to represent and explain, using concrete materials, the relationship among the numbers 1, 10, 100, and 1000, (e.g., use materials to represent the relationship between a decade and a century, or a century and a millennium).