Onion Experiments

Today A. was watching me cut onion for dinner, and we were discussing the colours of onion. He said that the onion I was cutting was not "red onion" but "green onion". I said that most people call this type "brown onion" because the skins are brown. He asked if there were any "black onions". I said if onions were black it was probably because of mould and you shouldn't eat them. Then I shared some information with him; that although the skins were brown, some people get yellow colours out of them.

Left: cold water - clear / Right : boiling water - yellow

"Can we do that!?" he asked. I said yes but I wasn't sure whether it would work better with hot water or cold water, so we decided to find out. We got two identical glasses and two piles of onion skin as similar sized as possible, and filled the glasses at the same time, to approximately the same height. I explained that this was to make sure that the only difference between the two glasses was how hot the water was. I tried to explain to him why it was that you want to make each cup as close to the same as possible, but I doubt that the theory went in the first time. This is the sort of thing he is likely to learn over many different experiments and probably only when doing them for himself, rather than having me help him with the steps.

Something else that I noticed is that he described the experiment really well. He wanted to make a video clip of it, so we did that. He even used "left" and "right" accurately. He noticed that if you get something wrong while filming, or someone yells in the middle of it, or something unplanned happens, you have to go back for another "take". Making videos can be a time consuming process! A. took a couple of photos of the last step of the experiment where we added a couple of face-cloths to the glasses to see if they would take the colour of the water. He separated them and took a picture of the glasses sitting apart.

He likes being able to record what we have done in the day to show his Dad. I guess I should point out to him that he can always show his family and friends all over the world if we put his findings on the internet. He's probably a long way from knowing what a scientific control is, but if we keep doing experiments together, and I keep explaining the steps as we go, he will probably take it onboard eventually, but in his own good time.... and what a good time he is having!