| | Understandings of Consequence > Curriculum Modules > Density > Introduction > Challenges in Understanding Density |
 | | Many density units emphasize that density is a property of materials, related to different "material kinds." While this unit does introduce the idea that density is a property, it also alerts students and teachers to ways that this concept can be problematic for learners as they try to extend their understandings to more complex phenomena. |
 | | There are a number of reasons, from a cognitive and perceptual sense, that students would be inclined to focus on the weight of an object (and miss its density), or focus on the sinking or floating object (missing the role of the liquid), locating the cause of sinking or floating in the entity itself. |
 | | The impact on density due to atomic mass and to the strength and structure of atom and molecular bonds is outweighed by how spread out the atoms and molecules are due to pressure and temperature. |
| pzweb.harvard.edu /ucp/curriculum/density/i_challenges.htm (2435 words) |