A hands-on activity is presented for elementary school students to discover the composition of matter and its consequences on chemical and physical properties. Natural forms of carbon (coal, graphite and diamond), synthesized forms (charcoal and activated carbon), and the differences in their physical properties are listed and discussed. Students build a flat hexagonal portion of the graphene sheets of graphite and a tetrahedral portion of the 3D structure of diamond. They experiment with conductivity of a graphite pencil and compare it with that of a wood stick and a copper wire. They also explore adsorption properties of activated carbon by decolorizing a grenadine solution. This activity develops manual skills and collaborative work. Students learn how to select appropriate observations for producing an experiment report both orally and by writing.