To understand how a thermos flask works we had a go at making our own! We learnt that the aluminium foil is like the reflective lining of the inner chamber of a flask and this prevents radiation, the heat is reflected back towards the liquid. The gap between the two bottles represents the vacuum in a flask, which the heat can't travel through, preventing conduction. Finally the stopper on the top prevents convection, the movement of warm air out of the flask and cool air moving into the flask. We all managed to make a thermos flask and we are looking forward to testing how good they are at keeping liquids hot!