During our Simple Machines unit, we learned about screws.
Key concepts of screws
Concept 1: A ramp wrapped around a rod
- A screw is an inclined plane (ramp) wrapped around a central rod.
- To illustrate: Show a picture of a very long highway ramp or very long staircase. Talk about how it might be impractical to have such a long ramp, so sometimes they wrap this into a screw shape – show a picture of a spiral parking garage (like at Sea-Tac airport) or a spiral staircase. (Here’s a PDF of the photos I found as an example. I don’t have copyright permission on these, so you should find your own.)
- Another illustration: Find a picture of a very steep path up a mountain (an inclined plane) and a switchback path (similar to a screw). By wrapping the path back and forth and back and forth, it’s more climbable.
- Activity for the kids to experience this concept: cut a triangle of paper. Mark the “ramp” side of the triangle. Roll the paper up around a pencil, and it becomes a screw. (Note: you could use these papers to make paper beads for a necklace.) Also, see snack ideas below.)
- Project to build: we made this… And here’s the tutorial on how to make a spiral ball ramp.
Concept 2 – Rotational motion to vertical motion
A screw takes rotational motion and turns it into vertical motion. When you turn a screw, it moves down or up, depending on which way you turn.
- To demonstrate / let kids experience it: take a very long bolt. Spin a nut around it. You can see that the nut travels up and down the bolt. You can give kids a dish of nuts and bolts and have them play with this.
- See the toy drill set described below.
- Alternate demo / experience: Take a peanut butter jar (or similar jar), and screw the lid on – pointing out how it travels downward, then unscrew it, pointing out how it travels upward. Give children jars and lids to try this out.
Concept 3 – Screws hold things together
- To demo: use two boards – hammer a nail through them to attach them. Then pull them apart. Then attach them with a screw. Show how you can no longer pull them apart. (Note: as always, test your demo before class to make sure that it works well with the exact materials you will be using!)
- Kids’ experience: See workbench idea below.
- To help them remember which way to turn, teach them: Righty-Tighty, Lefty-Loosey. Right is clockwise and it tightens the screw, Left is counter-clockwise and it loosens it.)
Concept 4 – A screw can move things
- Possible illustrations: an Archimedes screw can lift water up hill – one of the earliest water “pump” mechanisms. A grain auger is used to lift grain from trucks into grain silos. When you drill a hole, the drill lifts the cut wood up and out of the hole.
- To demo / let kids experience: Use the Archimedes screw or grain auger described below.
Bolts: We had a big bin of these building toys in the classroom – I unfortunately don’t know what they’re called, and I don’t think they’re still available! But, they’re big screws and bolts and plates and cubes and wheels to attach together with the bolts. There are lots of other nut and bolt toys that exist.
Drill: This toy drill set has a battery operated drill driver that allows kids to screw bolts into the board, then reverse direction and pull them back out. Very popular with lots of kids.
Workbench: You could offer boards, screws, and screwdrivers, and let children screw real screws into real boards. (You might need to use a nail to make some pilot holes to get screws started into the wood.) I think this is totally reasonable for kids age 5 and up. For kids 3 to 5, you have to use your judgment. I would do it if I were working one-on-one or in a small group of kids. But in our larger class, we used toy hammers and golf tee “nails”, plastic drywall screws or non-pokey screws and a screwdriver.
If possible: put out some screws with wide threads and some with tight threads. They could see that wide threads take more effort to screw in. Tight threads mean less effort, but you have to rotate it many more times to move the same distance.
Right Tool for the Right Job: Put out a collection of screws with phillips, flat, hex heads, and a piece of styrofoam to screw them into. Put out 4 tools: phillips screwdriver, flat head, allen wrench, and wrench. Kids figure out which goes with which.
Our Simple Machines Activity Set came with a small Archimedes screw. It works really well with a wide variety of materials – I’ve used it with M&M’s, rice, corn meal, and others. I like split peas / lentils best, as they move through it well and are easily cleaned up. In this video, I use water beads, because they’re what I had handy, but I wouldn’t use them in a kids’ activity, because if you’re not careful, the screw will break them up into little bits. I like this toy because it’s REALLY easy to clean.
I also found this great toy Grain Auger. It’s really cool and easy for kids to use. BUT it doesn’t work with a wide variety of sensory items. Bigger items jam it, and if kids are careful, they can back it up and unjam it, but most kids just crank it hard in the same direction to try to undo a jam, and I suspect someday that will break it. Also, in order to clean it, you’ll have to use a screwdriver to completely dismantle it – I haven’t attempted this yet. For class, we used it with cornmeal. We just put in some containers to fill. Next year, I want to put in a tall cylinder (maybe an oatmeal container) that would be similar to a grain silo, and then post a photo of a real grain auger and silo.
The Learning Resources Sand & Water Set includes a small and simple Archimedes screw to use in the water table. I haven’t had a chance to test it yet.
Snack: You could use refrigerated crescent rolls – they come out of the pack as triangles (inclined planes), and you roll them up into screws. You could also make pigs-in-a-blanket, and wrap the ramp (crescent roll) around the rod (hot dog).
You could use an Apple Peeler / Corer. These basically involve mounting an apple on the end of a screw, and as you turn it around and around, the screw pushes the apple forward into a blade, peeling it, coring it, and slicing all in one move.
Take Home Challenge: Make your own Archimedes screw: Here are a few possible ways to do that. I have not tested them.
Using paper and a plastic bottle: See directions here: http://iijuan12.hubpages.com/hub/lever-and-screw-simple-machines-lesson-plan and an example here: http://highhillhomeschool.blogspot.com/2013/05/hanging-gardens-of-babylon-archimedes.html
Wrapping tubing around a stick or pipe. As in this video: https://www.youtube.com/watch?v=NsAd7SlCpZ0 or as shown here: http://homeschoolden.com/2013/11/15/simple-machines-unit-screw-hands-on-activities/
Here is a paper model of an Archimedes screw: http://www.robives.com/blog/archimedes. They say it can be used to transport sugar.
Books: Check out my post on Simple Machines book series. There is a book called Drew the Screw which sounds great. The Amazon description says: “The pencil draws, the tape measures, the saw cuts and the drill makes holes. Together with the boy, they are building a treehouse. What can you do? the tools ask Drew. Drew worries that he can t do cool things like the other tools. But when boy comes for him, Drew is surprised to get a job that’s not only important but just right.” It’s OK… but not great.
Note: All the activities described in my posts are from Family Inventor’s Lab, a parent-child cooperative class in Bellevue, WA. We are a play-based, STEM focused class for preschool through early elementary (kids age 3 – 7). We do a wide variety of fun, hands-on activities to learn about Science, Tools, Engineering, Nature, and Art. We also sing songs and read stories. Most of our activities are cheap, easy, and use everyday materials that most families would have in their homes (or their recycle bins!), so that our activities are appropriate for classroom teachers, parents who homeschool, or after school programs.