⁃What does it look like to begin reasoning early about density before definitions and formulas?
⁃What sorts of classroom activities and teaching approaches might support this?
Although it may be too early to formally introduce density in grade 4, it is not too early to begin reasoning about the concept. In the present examples, density is broached indirectly in activities of: (1) ordering materials of equal volumes by weight; (2) ordering equal weights of materials by volume; and (3) inferring the materials of covered objects. Students eventually realize that certain materials are relatively heavy or "heavy for their size" and that this is different from their scale weight. In grade 5, this working knowledge of density comes in handy when students face issues related to change of state—for example, when liquid water transforms into a larger volume of ice having the same mass.