How can you set up an investigation to find which materials can and cannot be changed back to their original state? - Teacher notes

To set up an investigation to determine which materials can and cannot be reverted to their original state after undergoing a change, begin by selecting common materials with varied properties. Pupils are to work in pairs and focus on a list of twelve materials provided. The investigation will explore changes in state through the processes of heating and freezing, with water being the primary substance used for mixing with the other materials.

Each pair of pupils will choose up to five materials from options such as salt, sugar, vinegar, sand, and fruit juice. Initially, they will dissolve or mix these materials with a specific quantity of water and then freeze the mixture. Observations should be recorded, noting any changes in the materials' states. Attention should be paid to maintaining fairness in the investigation, ensuring that variables are controlled. Following this, the materials will be added to boiling water, once again under strict supervision, to observe the effects of heat. The results of these experiments will provide insights into the reversibility of the changes and will form a basis for understanding processes like dissolving, filtering, and evaporating in subsequent lessons.