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I think all children are natural scientists. They are full of questions, love to experiment, and love to learn more about the way the world works. In my quest to keep the spark of joy in discovery alive for my children, I actively seek out science kits, learning toys, anything that helps them explore and understand the natural world. They also love crystals - and growing things, so this looked like a brilliant idea. because I have two boys, I bought two packs at roughly £5.00 each.
What's in the box?
A bag of stones - about 6 or 7 bits of gravel. There is nothing else. But perhaps they are rare or unusual stones? The box doesn't tell us what they are, but they react very much like limestone to vinegar so a Google search of "limestone + vinegar + crystals" yielded enough information for me to be virtually certain that these are in fact common limestone. They look just like the rocks laying out in my garden, only smaller and almost certainly are just like the stones laying out in may garden.
In addition to stones, you get a box. This tells you to pour vinegar over the stones and leave them in a WARM room with warm all in caps, stressing that a windowsill will not be warm enough. Once the crystals start to grow, you are instructed to add food colour and theoretically you'll end up with something that looks like the picture above. Of course the picture is misleading. There is no chance the crystals are going to be the size they appear in the picture. I have since looked up several pictures of this type of crystal and they most certainly are not the size shown here. Keep in mind the stones you get to grow these on are perhaps 1" long. They are basically the size of the stones in my fish tank. I suspect a picture was taken of one these bits of gravel using quite a lot of zoom and then the picture of the box added with photo shop.
There is no description of the science involved, no explanation of the fact that the stones hiss and bubble slightly when you add vinegar to limestone it reacts with the calcium to form carbon dioxide, nor is there any mention of the fact that the calcium becomes dissolved in the vinegar because vinegar is an acid and then reforms into crystals as the liquid evaporates, so if this works, without proper explanation, this looks more like a magic trick than science, and I don't really see what the children learn from it.
What's not in the box?
White vinegar, food colour and a growing dish.
This was a dismal failure for us, but after researching online, I suspect it may be because our house isn't really warm enough. Crank the radiators up to full blast and leave them on 24 /7 and you'll most likely have far better results. Or you can cheat. and heat everything up. I didn't know that before looking everything up online. Next time I am definitely cheating.
We didn't bother to add food colour to our crystals. They are smaller than a bit of rice and look more like bird poo than crystals. You do get a hard white material at the bottom of the bowl eventually. Apparently if you keep breaking this crust up and adding back into the vinegar it will result in better crystal formation as well, but again , this is something I learned online, it is not mentioned in the instructions. Needless to say, the children were disappointed with this, but we will try this again though. Next time though, I'll just look for rocks in the garden, or if I want to buy limestone rocks specifically, I'll visit B&Q where I can buy a large bag of limestone rocks for landscaping for only £3.08.
My sons would give this the lowest possible rating of just one star, for the simple reason that it did not work. While I am not overly pleased at the idea of paying a tenner for a few measly rocks, to be fair, I would not have thought of pouring vinegar on limestone to make crystals if I had not bought the kit first. And if I could get some idiot to pay me a fiver each for the tiniest bag of stones from my garden, I'd do the same. In all fairness I must also admit that I did go against the instructions by placing this in a windowsill, but it was just over a radiator, and we do have double pain windows, I couldn't really think of any place warmer, but in retrospect, I should have put these in a tray in the boiler over the oven where the heat from baking would have heated the mixture every time I cooked. Had I known heating the mixture would lead to better crystals, I would have done so, I thought it only had to evaporate. But I do feel the picture is misleading, and that the instructions are inadequate. As such I am giving this one star as well.
My one consolation is that my husband has no idea this was common limestone. If he did - I'd never hear the end of it. Every time a stone was tossed in the garden or he noticed one laying about he'd be lifting it and asking if I wanted to pay a fiver for it - not to mention telling everyone how his wife spent £10 on a few ordinary stones. Not that I wouldn't wind him up forever if he was the one to have bought them, but as far as slagging it is better to give than to receive.