Transformations of Matter
In this unit, students study the transformations of materials and substances. By comparing the characteristics of the materials, such as color and physical state before and after a transformation, students learn that a transformation implies the modification of the final system in relation to the initial system. At the beginning of the unit, students study the initial and final characteristics of systems and objects that undergo transformations. They also melt flaked paraffin and solidify it in a new shape, recognizing that the change of physical state does not necessarily modify the composition of some substances. Next, students compare and contrast physical and chemical changes by performing experiments that result in new substances or materials. They work with the properties of a new material, dye. Students learn that pigments can be natural or synthetic and they observe one of the first pigments synthesized by human beings. Then, students mix a pigment, a solvent, and an agglutinant, all of which are necessary to fix the dye to the painted surface.
In the last few lessons of the unit, students are challenged to consider raw materials used to make various products. Students recognize that chemical and physical transformations can make it difficult to identify the original state of matter. Students will have the opportunity to discuss the care, use, and value of natural resources, as well as the production of garbage created by a consuming society, which ultimately threatens such resources. Students produce recycled paper and compare properties of different papers. Students also experiment with the effect of different additives used by the paper industry.