Rock Tumbling

After my son showed an enduring interest in rocks and minerals, I purchased the National Geographic Professional Rock Tumbler. It comes with the reusable tumbler, a pound of rocks, a color informational booklet, the grit used in tumbling, a strainer, and a few jewelry accessories. I find it is the perfect centerpiece for a unit study on the rock cycle and can pair well with earth science, chemistry (intro to the elements), and geography. Whatever direction you and your kid want to take it.

What I love about rock tumbling with a 5-year-old is how it teaches patience. The process takes a few weeks to complete, but you get to check on your rocks every few days to see how they have changed. If your child is ready to keep a research notebook, this would be an opportunity to practice simple observation and record keeping.

Here's what the rocks looked like on arrival:

The tumbler came with 1 lb of rocks. This is what they looked like before tumbling.

To polish these rocks, there are four packets of grit that you use in series, starting with the coarsest. The tumbler consists of a motor with belts and a watertight barrel. Getting started takes only a few minutes and my son was able to do most of it himself. Just open the barrel, place the rocks inside with Grit 1, then pour enough water to cover them. Seal up the tumbler, place it on the motor, press start...and be patient. The first step takes 3-5 days at high speed.

This is what our rocks looked like after four days being tumbled with Grit 1:

These are the same rocks after about 4 days of tumbling. Smooth, but not shiny.

My kids were impressed and liked comparing the before photo to the smooth rocks in front of them! They looked shiny when wet and dull as they dried off.

The messy part of this project is switching between grits. You can do this outdoors or set up a waterproof table covering. When you open the tumbler, you are left with the rocks in a slurry of rock powder, grit, and water (which cannot go down your house's plumbing). We went outside and poured the contents of the tumbler through the strainer into a disposable plastic tray (thanks, IHOP takeout!). We rinsed the rocks to see if they had rough edges and decided they were smooth enough to move on to Grit 2. Then we poured the slurry off outside and set up the next round of tumbling.

I find it is hard to mess this project up. If the rocks hadn't been smooth enough, we could have poured the slurry back in the tumbler. If you run it too long, the rocks are just smaller than the could have been. The time it takes to wear away the rough spots varies depending on the hardness of the rocks you start with. If you have your own rocks, you'll want to tumble batches of rocks with similar hardness. Time to pull out Mohs scale! (We are already collecting rocks to use in a second batch. I am excited to see what happens to our local finds when polished!) 

I will post updates after we are finished with Grits 2, 3, and 4. If you are thinking about buying this kit, here are a couple more things you should know:

After the first batch, you'll have to get more grit and a source of rocks if you want to do more. (There are many options online for rough rocks if you aren't planning to collect your own. Grit can be purchased on Amazon, and I'm still looking into other options.) This kit comes with only enough grit for one batch. The tumbler itself is reusable and is reputed to last years.

It is a bit noisy. I find it is not quite as loud as my dishwasher. In fact, it would make a great alternative to a white noise machine! We were slow to start using it because the kids didn't like hearing the sound at night, so we ended up putting it in the garage.

I picked mine up on sale, but there is also a cheaper version by the same company. I have not tried it out, however.

Got questions? Let me know in the comments!

(The links in this post are affiliate links. It does not change the price of the items, but if you purchase something I will receive a small commission.)

Bringing Nature Inside: AntWorks Ant Habitat

Did you ever try to make an ant farm when you were a kid? I remember being fascinated by the workers and especially the queen, then disappointed when the colony didn't survive long enough to get established.

Fast-forward a couple decades to the present day, and my son got a space-technology ant habitat for his birthday. This thing is brilliant! It looks simple: A container filled with a clear gel. But the gel does double duty, serving as both the tunneling medium and as sustenance for the ants. It was originally designed to allow the study of ants in space, where the gel would not collapse during re-entry the way soil would. The at-home version is about the size of a paperback book. It is not designed for a colony, but more for the opportunity to observe ant tunneling behavior. (No queen required!)

So my son and I opened it up and he immediately asked the most obvious question--where do we get the ants? Well, you can order a package of harvester ants from AntWorks, but living where we live, I thought it would be no problem to find some on our own. (Let's be honest, I would not have been surprised had the ants found the habitat without any help from us.) Hurray for ant hunting! Our first attempt involved a bit of pancake syrup and a plastic tray. We got a whole mess of tiny little ants, plopped them into the habitat...and then watched them squirm and squeeze their tiny tushies out through the two minute airholes, leaving us with an empty habitat. For our second attempt, dear hubby took our son to the park and went "fishing" for ants. Syrup on a stick, because we're high-tech like that. A fun time was had by all. I'm still not sure if they are leafcutters or harvesters, but we got about 16 ants ready for their new home!

The product manual says to expect waiting 24-48 hours to see tunneling. I was really crossing my fingers that we would get timely results that look like the ones in all the pictures... and man oh man we got some very smart ants! Or at least highly motivated! After one hour, they had started their first tunnel, down one side. Every time someone walked past the habitat, we automatically stopped to watch. We could see the ants using their mandibles to tear off pieces of gel, then carrying the crumbs to the service. At his bedtime the first night, my son asked us to check up on the ants. They slept on the surface, without sufficient space below "ground." The next night they slept in their main chamber (bottom left in the picture). Each day, we made predictions about where the ants would tunnel next, and crowed when we were correct. After three days of hard work (for the ants!), this is how it looked:

The ants now seem to be taking a break from tunneling, but they keep moving. I'm happy because we were able to snag some library books about ants to see if we can find out more about why ants tunnel the way they do. And every morning, we check to see if they have done any more excavating.

If this looks like just the thing for your budding scientist, you can get a version of AntWorks with illumnation or without (affiliate links). I can even imagine this being a fun alternative to keeping a fish at the office!