# Screws

An updated version of this post can be found at https://inventorsoftomorrow.com/2016/10/24/screws-simple-machines-activities-for-kids/

During our Simple Machines unit, we learned about screws.

Key concepts of screws

1. A screw is an inclined plane wrapped around a central point. You can illustrate this by showing kids a picture of a spiral staircase or a spiral parking garage ramp (like at Sea-Tac Airport). You could also find a picture of a mountain with a path going straight up (an inclined plane) and a switchback path crisscrossing its way up a mountain. With the distance available, the inclined plane would be really steep… by making it into more of a screw, it’s more climbable.
2. A screw takes rotational motion and makes it vertical motion. When you turn a jar lid around, it moves down or up, depending on which way you turn.
3. Screws hold things together.
4. A screw can also be used to move things: 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 in a board, the drill lifts the cut wood up and out of the hole.

Demonstrations

To demonstrate the inclined plane concept, cut a triangle of paper. Mark the “ramp” side of the triangle. Roll it up around a pencil, and it becomes a screw. (We had this as a hands-on activity for the kids to see this idea.)

To demonstrate idea #2, take a very long bolt. Spin a nut around it… kids can see that it travels up or down the bolt.

To demonstrate idea #3, you could

• 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
• use two pieces of thick Styrofoam and a golf tee instead of boards and nails

Explorations

We had a big bin of these toys in the classroom – I unfortunately don’t know what they’re called! But, they’re big screws and bolts building toys.

We had this toy drill set, which has a little battery operated drill driver that allows kids to screw bolts into the board, then reverse direction and pull them back out. Very popular with some kids.

You could offer a collection of jars that children could screw lids on and off of.

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 them started into the wood. Optional: you could have 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 more times to move the same distance.

Snack: A possible snack would be to use refrigerated crescent rolls – they come out of the pack as triangles, 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).

Archimedes screw: I really wanted to make an Archimedes screw for the water table and/or the sensory table, but I ran out of time. I’ve found a few possible ways to do that:

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.

For our next class on screws, I have found a few products to try out: a toy Grain Auger to use in the sensory bin, and a small Archimedes screw from a Simple Machines Activity Set that we can use with M&M’s or in the sensory bin.