Thermochromic paint can be made in the laboratory and used for temperature sensing by observation of colour changes. This can be illustrated by an improved method of showing comparative conductivity of heat by different materials, and an amusing method of indicating approximate temperatures of liquids in drinking glasses. The fabric Lycra, used to make stretchable close-fitting clothing, can be made electrically conductive (Electrolycra) by using a fine coating of metal. The changes in resistance when the material is stretched can be used as a model force-sensor and to illustrate measurement of duration of a collision and the reaction force of a dynamics trolley.