Memory MATTER AND ENERGY, CALP, YEAR 1Version en ligne Listen, read and match. par Rafael Rodríguez Pérez Energy can be produced from renewable sources. Materials can be natural or manufactured. Pure substances are made of 1 thing. Materials can be rough, smooth, soft, hard, rigid, flexible, transparent or opaque. Mixtures are made of more than 1 thing. Energy can be produced from non-renewable sources. Some materials change their state.