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