This RECAST activity uses two cylinders of equal volume but surprisingly different mass to help students grasp the concept of density. As an intensive quantity, you can't directly measure or observe density. It is non-obvious and must be inferred. Making it obvious helps students to realize that they have to reason about mass and volume relationally in thinking about density.
Download instructions and analysis for this activity. (PDF, 204KB)
This RECAST activity asks students what will happen when two pieces from the same candle, one bigger, one smaller, are dropped into two different beakers of liquid. It encourages students to switch from a simple linear model where they think the weight makes it sink or float to a relational causal model that takes into account the relationship between the object and the liquid.
Download instructions and analysis for this activity. (PDF, 244KB)
