In our current science topic of ‘Solids, Liquids and Gases’, year 4 have been investigating the properties of gas. As most gases cannot be seen, smelt or felt, their properties are difficult to examine. The children had to devise a way to measure how much carbon dioxide gas there was in a cup of fizzy lemonade. Knowing that gases have weight, they planned to weigh the cup of fizzy lemonade, stir it until the gas had escaped, then weigh it again. The children worked out that the difference in weight would be equivalent to the weight of the gas that was in the lemonade. The investigation was a huge success with every group measuring a reduction in weight of up to 4g. The children could confirm that carbon dioxide gas did have weight and that fizzy drinks weigh more that flat drinks.