In Science this week, Upper School learnt about irreversible changes of matter. Firstly, we discussed what reversible and irreversible meant. We related this to materials that we have already investigated such as water and chocolate. Next we discussed what makes something an irreversible change. Burning wood, cooking eggs, baking cakes were ideas that they came up with. Next, I demonstrated an example of an irreversible change by mixing bicarbonate of soda with vinegar and getting the class to observe the way it fizzed, foamed and inflated the balloon with carbon dioxide on top of the bottle. The children noticed that after the chemical reaction, the vinegar didn’t smell anymore and was much more like water. 
Finally, I told the children about casein plastic and how it can be made by a chemical reaction between hot milk and vinegar. The children tried this out for themselves and observed the interesting way the milk changed. They were amazed at the results and were able to make a shape with the ‘white dough’ that was left after filtering. They will continue to observe these dough shapes over the coming days to see what happens to them…

Science-Irreversible Changes