Prior to using this narrative, have learners create their own model of a cell in their notebooks using whatever background information or experience they might have. While exploring the narrative, ...

It's no coincidence that our bodies feel a little creakier as we age. The trillions of cells that make up our skeleton age too, and some change in ways that weaken the very structure of our bones.

This article was originally featured on Knowable Magazine. More than 1.5 billion years ago, a momentous thing happened: Two small, primitive cells became one. Perhaps more than any event—barring the ...