Grade 5
Students use pen-and-paper models and a computer simulation to solve a puzzle: how can water take up more space as it freezes but weigh the same amount? The teacher’s careful choices regarding which resources to put into conversation with one another support her students to make progress on developing an explanation.

Grade 2
Maya and her classmates draw on materials and gestures as they develop mechanistic explanations of maple seed travel.

Grade 5
Students make claims about what factors matter for decomposition. They use evidence from an investigation to support their claims, and they begin thinking about explanatory mechanisms for why a particular factor matters, making connections to the life cycle of mold.