Have you ever had to sort coins? Or separate lots of game or LEGO™ pieces by size or color? When you only have a few, it's easy to simply sort them by hand. But the more pieces you have, the more challenging sorting becomes.
Imagine trying to sort thousands of items by size in just a few minutes! Many produce growers have just that problem. Foods like potatoes, tomatoes, tree fruits, nuts, and berries have different uses and prices depending on their size. Growers rely on mechanical sorters to quickly divide a large crop into groups that can then be processed or sold separately. The video below shows just such a machine sorting mandarin oranges. As the oranges move through the machine, fruits drop into bins designated for specific sizes.
Have you ever used a kitchen sifter to separate small grains of flour or sugar from larger clumps? That same process is used on a larger scale to sort large quantities of aggregate material into separate groups. Aggregate describes a material that is a mixture of particles that are different sizes.
The earth resources industry deals with a lot of aggregate material. Mining ore, for example, is a mixture of rock, gravel, sand, and mineral particles. The energy required to retrieve valuable metals and minerals from the ore can vary with the size of the material. So it is more efficient to sort it prior to processing. It takes large machines capabable of moving heavy material to do this.
Here's a large sorting machine that quickly separates aggregate material into 3 separate piles based on size. Image found on For Construction Pros website.
Sorting and screening machines greatly improve industrial efficiency since they use mechanical processes to sort materials in significantly less time than humans can manually.
For this activity, try designing and constructing a sorting machine using simple materials. Your machine must be able to properly sort 25 each of two different small sphere sizes (50 spheres in total). The goal is to design a sorting machine that is both accurate (sorts the spheres properly) and efficient (sorts the spheres in the least amount of time possible). Your design parameters are as follows:
Check out our Helpful Tips section for a list of suggested materials, some simple sorting machine design examples, and ideas for some important design considerations.
Remember, your sorting machine needs to be gravity-powered. This means that the spheres can be sorted by size or weight. It’s up to you to decide which will work better. You can find examples of each kind of design on the Science Buddies website, along with a vides that show each one in operation.
Here is a video of a simple coin sorting machine made from cardboard. It can be adapted to be an automatic coin sorter with the addition of a small motor to create a vibration to keep the coins moving.
It's possible to design a marble sorting machine made entirely of paper! This video shows how paper can be rolled to create beams that can support other parts.
Suggested sorting machine materials
If you enjoyed this activity – take it a step further with more design challenges!
Try designing a machine that sorts objects by color (like colored candies). Check out the following link for an example of a machine that sorts by color.
Photo credits:
Marbles image by Ulrike Leone from Pixabay
Using simple materials, design and construct a gravity-powered machine that can sort two different sizes of small spheres like beads or marbles.
*Spheres could be wooden or plastic beads, marbles, spherical candies, or other small round objects. Check the bottom of the page for materials you can use to build your sorting machine.
Always check with a parent or guardian before you start a project and make sure it is okay to use materials you find around the house.
