Sorry about the science delay. I’ve just been busy. I decided to give us an extra week looking at minerals and to focus especially on salt. I wanted the kids to review the ideas we’d already covered about how elements combine to make minerals and minerals combine to make rocks. I also wanted them to learn that salt is a mineral that we need and use every day. I wanted them to see from the example of salt that different minerals have different properties that we can find useful in different ways.
For rocks and minerals, last week’s books were a good start, but we also found an older title, What is a Rock? by John Syrocki at the library. This is a series from Benefic Press that also includes other titles we’ve checked out, such as What is Electricity?, but which I’ve not mentioned because most of them are outdated. However, I really liked this one and the information was fine. Like rocks themselves, the most basic information about rocks hasn’t changed too much in the last half a century. We also took at look at Jump Into Science: Rocks and Minerals as well as the Let’s Read and Find Out title Let’s Go Rock Collecting. Once we’ve finished with chemistry, we’re going to come back to rocks and minerals, so I didn’t feel too much pressure to get everything in this go around.
For the topic of salt, we had an amazing book, The Story of Salt by Mark Kurlansky. This is a picture book version of a popular nonfiction title of the same name and author. There have been a lot of good young adult editions of popular nonfiction books, but this one the first I had seen to be transmitted to picture book. However, it worked so well! The book is much more focused on the history of the topic, but it’s still a great read and when else would you do it but while studying minerals? From Sea to Salt by Robin Lerner is intended for younger kids, but we didn’t even end up reading it because I liked the Kurlansky book so much.
I’m afraid we’ve been cheating on our free resources more and more since I got Discovery Streaming and BrainPop. In addition to the videos we did last week about minerals, we did the BrainPop video about salt this week. Also, we watched this nice ten minute video called Geologist’s Notebook from Discovery Streaming. It was very schooly, but also very succinct. For one more on rocks and minerals, try this short but nice one about the differences on Youtube.
For salt, there’s a great episode of How Stuff Works about salt. You can find it on Discovery Streaming here. Or you can watch this clip about salt mines from the episode. Or this one from National Geographic embedded below:
For activities, we began by just thinking about salt. I gave the kids a little pile and let them touch it. BalletBoy immediately consumed his whole pile and asked for more. The child has a total salt addiction that I had no idea was even there. Next, we did some of the simplest experiments you can with salt. We watched it soak up water and then we watched it melt ice. Well, we didn’t exactly watch that part, we set it up, watched a short video, then observed, which is what they’re doing in the picture below. We also all observed how dry our hands felt after touching the salt so much.
Next, we set up an experiment from Janice Van Cleave’s Earth Science for Every Kid where you mix a cup of water and three tablespoons of salt then allow the water to evaporate to form what are basically salt flats. It can take up to three weeks, so we’re not done. It’s currently just a bowl sitting on a shelf. I’ll let you know how it comes out. The connection I hoped to make was between the chemical formula and the shape we see after dissolving the water and evaporating the salt.
A much quicker version, which will yield different results because the crystals aren’t square like salt, can be done with Epsom salts. They’re available pretty cheaply in the drug store, in case you, like me, don’t just keep them around. For this experiment, mix a cup of water and three tablespoons of the salts. However, you won’t need that much. You just need a thin layer poured over a piece of black or dark construction paper inside a small, flat-bottomed container. I used the lid from our Thinking Putty, but a jar lid would be fine. By the next day, the water has evaporated and left the crystals. Be sure to flip up the black paper because the crystals on ours were much cooler underneath than on top. We talked about how this had a different chemical formula.
Finally, mostly because the kids begged and begged, we set up to make rock candy. Obviously, this isn’t salt, it’s sugar! We talked a little about crystals and their formation, but I didn’t dwell too much on this, honestly. We followed the directions here and I’m hoping that there’s rock candy growing in those murky jars that the kids overused food coloring on. I’m really hoping.
ETA: I wrote this post a couple days ago and we’ve since checked the rock candy. No crystal growth! Drat! We’ll have to try it again.