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