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Science ROCKS: How to teach kids fun concepts with a Rock Tumbler #31daysofactivities

Today in our 31 Days of Activities, we have a lovely STEM activity for the kids to help teach them just how much Science Rocks! This is from the Hess Un-Academy site, so do take a look at all the wonderful resources they have on site too. Has your child ever stopped to pick up an interesting rock in the playground, or a pebble on the beach? “Look Mom, this rock looks like a heart!” If your kids love rocks, you might consider enjoying a rock tumbler science activity with them.

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How to teach kids fun concepts with a Rock Tumbler

Rocks come in many different shapes, colors, and textures—which make them a great (and very accessible and affordable) way to teach basic concepts. You can teach toddlers how to sort and count. You can ask preschoolers to spot the differences, which is the first step to analyzing and abstract thinking.

For older children aged 7 to 10, who are starting to learn about the Natural World in their Science classes, you can also use rocks and a rock tumbler to demonstrate mechanical weathering: the geological process where water, friction, and weather break down rocks and minerals.

Rock Tumbler

What is a Rock Tumbler?

A rock tumbler has 1 to 2 containers or barrels that you fill with water, an abrasive material like grit, and water.

A rock tumbler holds one or two containers of rocks, abrasive grit, and water. There are two kinds of models: rotary tumblers which turn the barrels, and vibratory tumblers that shake them. Vibratory tumblers are more expensive, but can really polish stones until they shine.

If you’re good with wood crafting, you can make your own rock tumbler. Or, you can get rock tumblers on Amazon or other websites. This is a Rock Tumbler that is a little more affordable for kids in the UK from Trends UK. We are sure there are great alternatives in the US and globally too.

Rock Tumbler learning activity

What to do first

First, talk about different kinds of rocks. Show them pictures from the Internet, including famous rock formations like England’s Old Harry Rocks (a UNESCO heritage site), Ayers Rock in Australia, Bolivia’s Arbol de Piedra, and more.

Then, explain the concept of mechanical weathering and challenge them to find different kinds of rocks. You can go to the playground or park, or make a special trip to the beach or a forest/mountain trail.

Bring the rocks home and take pictures of them. Place them in the rock tumbler. Ask children to observe how the rocks change on Day 3, Day 6, Day 9 etc.

Rock Tumbler instructions

Rock Tumbler for Kids

Every rock tumbler will have minorly different instructions but here is the overall idea.

  1. Gather your rocks
  2. Rinse them off
  3. Place them in the tumbling container (remember you can get one on Amazon if you don’t have one already),
  4. According to your tumbler’s instructions, add the grit and water and close the lid
  5. Set your tumbler to run in a safe place where it won’t be disturbed
  6. Check your tumbler after about 3 days. Observe the way the rocks have changed. If needed, add more water or grit (follow your tumbler’s specific instructions).
  7. Let run for another 3-4 days and repeat step 6.
  8. Repeat steps 6 and 7 according to your tumbler’s instructions for about a month
  9. After a month, pull out your rocks
  10. Rinse them really well
  11. Observe your newly polished rocks
  12. Talk about the changes your rocks went through and how these changes can be observed in ‘real life’.
Rock Tumbler to polish rocks with kids

Learning concept

The rock tumbler helps children understand how natural forces have helped shape the landscape. Mountains, canyons, and other physical features of the land have slowly been shaped by water, friction, changes in temperature, etc.

Types of rock to put in a Rock Tumbler

These are the same forces that shape rocks they find, or the gemstones that are used in jewelry. Through the rock tumbler activity, they can see how it works, measure the time it takes for visible results to appear, and compare the results.

Kids Rock Tumbler and learning kids about rock types

Expand on the learning

  • Science. Depending on the age of your child, you can also introduce related scientific concepts like friction (demonstrate with a nail file or sandpaper), or explain more complicated processes that affect rock shapes like thermal stress, pressure, or haloclasty (salt).
  • Geography. Talk about famous rock formations or the landscape of the state where you live.
  • Art. Think of fun craft projects you can do with the polished stones.
Rock Tumbler to teach kids curiosity about the worl

Teach curiosity about the world we live in

Every child is a scientist. They are naturally curious, and as early as infancy will use their senses to explore and learn more about the world.

As parents, we can feed this curiosity with fun home experiments. The rock tumbler activity gives a clear, concrete demonstration of a process that has been shaping the planet for millions of years. Water and gentle vibrations have carved out mountains and valleys, boulders and pebbles. So the next time your child picks up an ordinary rock on the street, he’ll know the backstory and think, “Wow, rocks ROCK!”

Raising Tomorrow’s Scientists

These moments can give your child a real love for science—and who knows, he may decide to make it a career. The world needs scientists, and currently, there is a shortage.

According to the United States Department of Education, only 16% of high school students are interested in taking up STEM. STEM is a special curriculum that focuses on four disciplines: science, technology, engineering, and mathematics. It prepares students for college courses (and eventually, careers) in computing, engineering, physical or life sciences, and Math.

Many families are so interested in these subjects that they find a STEM book or a STEM curriculum that their kids can enjoy. A good STEM book or STEM curriculum will guide your kids on a journey of self-discovery as well as a discovery of the world around them and how they interact with that world. Whether you are a homeschooler or a more traditional schooler, it’s always wise to invest some regular time into STEM projects.

Who knows, your child may take up STEM and be the research biologist who discovers a cure for cancer, the chemist who figures out how to reverse pollution in the sea, or the NASA engineer who builds the first colony on Mars.

But it all starts in building their interest today, through fun home experiments and an environment of learning and curiosity.  

Fun STEM Activities

If you're looking to create something fun with your kids then these STEM activities are for you! We hope you enjoy them.

Take a look at even more great STEM activities from the web below.

More STEM ideas from the web

Combine learning and fun with these STEM ideas from around the web.

See you back here very soon,


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Charlene Hess spent many years teaching kids before she had her own kids.

She now has 7 kids of her own, whom she has been homeschooling for the last 11 years. Charlene still teaches other children outside of her home but finds great joy in exploring the world with her family.

Charlene has participated in many leadership trainings with John C. Maxwell.

Charlene and her husband Benjamin blog about homeschooling and success principles for kids at Charlene also blogs about homesteading and emergency preparedness at

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