The Child’s Ideas for 5. Transformations

The Challenges of Learning about Transformations

in science, some of the most important things about these transformations are what doesn't change

Our perceptual systems are designed to attend to change in our environment. Even infants grow bored when they repeatedly encounter the same thing—the same toy, the same tone, the same smell, the same color, the same food—and often turn away or “tune out” seeing, hearing, or smelling the familiar thing entirely. They also show renewed interest and attention when they encounter something new. Attending to what changes is important. It signals something new has come into our perceptual field that needs to be checked out to understand what it is and whether it is a potential boon or threat—a new person, a new food, a new animal, an unexpected car or other moving object in our path of movement.

Thus, it is not surprising that children find the topic of investigating transformations of materials particularly engrossing and interesting. Children enjoy doing things, and find permission to pound, mold, break, rip, burn or otherwise “take apart” and play with materials both novel and liberating. Further, the changes that occur as they watch what happens when they crush or grind up things, carve, mold or reshape things, heat or cool things, and combine or mix things can be dramatic and surprising, especially when reactions occur, things change color or texture, or disappear entirely from view.

Children will naturally first pay attention to the changes they observe in those transformations. For example, grinding up a piece of hard wood produces something that has a totally different appearance—soft, light, and powdery. But in science, some of the most important things about these transformations are what doesn't change. For example, when materials are crushed into little pieces, the total volume and weight of all those pieces remains the same, as does the kind of material of which each piece is made. These constancies provide clues to some of the most fundamental physical principles (e.g., conservation of mass and matter) that will ultimately be useful in tracing matter across transformations until it appears to “disappear” entirely.

Challenges in teaching children about transformations include not only getting them to attend to what doesn't change, but also helping them understand why attending to these constancies is particularly important for science. Children will find these constancies more interesting and attention-worthy if they are asked to make predictions ahead of time about whether the volume or weight will change and then are asked to figure out ways to test or evaluate their predictions. Most children expect that the volume changes with reshaping or that things get lighter when they are ground up into little pieces, and are surprised to learn that they don't. But because these underlying constancies are not obvious based on casual inspection, it also take careful measurements and discussion of measurement error for children to notice them at all, along with discussion about how these constancies can be explained for children to be convinced that they really occur.

—Carol L. Smith