We are being chemists this half term and looking at the properties of substances and the changes they go through. This lesson, we talked about how to separate different mixtures such as flour and rice or sand and water and the children were able to explain that you could use a sieve or you could filter the mixtures. This is a reversible change. They then talked about how they could separate a solution of salt and water. They had some great scientific discussions about this before finally reaching the conclusion that evaporation will allow the reversible change to take place. The children made a salt water solution and placed it in dishes on the windowsill. Heat speeds up the process of evaporation. The children were wowed by how fast the water evaporated and that it left behind salt crystals.
