Category Archives: STEM activities

Catapults

Catapults are a huge hit with kids… being able to launch things into the air and across the room is always exciting!

There are LOTS of ideas online for how to build catapults. I want to present a simple series of catapults that show the evolution of an idea.

Supplies needed: pencil, popsicle / craft sticks, rubber bands, a plastic spoon, an object to launch (e.g. pompom or mini marshmallow or coins)

Stage 1

First, take a popsicle stick (the bar of your lever), balance it over a pencil (your fulcrum). Put an object (your load) onto the end that’s laying on the table. Hit the high end of the stick, the object launches. This is an easy depiction of the simple machine concept of levers (learn more about Levers here.)

You can also play with this idea – use a bigger fulcrum – use a longer lever. Like try a large spoon balanced over a rolling pin, or a ruler balanced over a marker.

Kids will have plenty of fun with this. Launching things is fun. But, they’ll soon discover that this is a weak catapult – we can get a lot better launch by evolving it.

Stage 2

Now, take two popsicle sticks: Use a rubber band to fasten them together at one end. Then slide a pencil (or three craft sticks bundled together) between the sticks until it pushes up against the rubber band. Set it down. Put your pompon (or coin) on the raised end, then use your finger to press down and release. The pom pom will fly much higher!

If the coin / pompom keeps sliding off the end of the bar, you can glue a lid to the end of the bar so you have a “bucket” to put your coin / pompom into.

Stage 3

After they’ve had a good time with this one, you can take this simple design to the next level by creating a spoon catapult. You’ve already got your two popsicle sticks banded together. Use a rubber band to attach a plastic spoon on one. (Here’s a picture from www.devincollier.com/how-to-build-a-simple-small-marshmallow-catapult/. to show you where to fasten it.)

Slide your pencil in between the sticks, as before (or use two or three popsicle sticks rubber-banded together). Now launch items from the spoon – your launch arm is longer, and you added the springiness of the spoon – does this increase the strength of the launch (i.e. does your object travel farther?)

Stage 4

Now bundle together 5 craft sticks to use as your fulcrum – this is what is shown in the picture above, and you can also find directions at http://cosmos.bgsu.edu/STEMinPark/takeHomeActivites/2012/MarshmallowCatapult.pdf

Is the catapult stronger with a taller fulcrum and more pressure on the rubber bands that bind the launch sticks together? What if you use 8 sticks in your bundled fulcrum?

Stage 5

Use longer bars to build the catapult than popsicle sticks. Maybe rulers? Rubber band them together at one end, and keep using your bundle of craft sticks as a fulcrum.

Continue to experiment… Here’s a very similar catapult built from a couple of wooden yardsticks, a piece of cork (used as fulcrum to separate the two sticks – you could use your stack of popsicle sticks) and some tape (could use rubber bands).

Testing and Tweaking

As you build a variety of catapults, test them. You can compare on two criteria: which designs launch the object the farthest and which launch it the most accurately (i.e. can you hit a target with it.)

For more STEM related activities, click on the word STEM in the right sidebar…

DIY Water Wall

9 Replies

When I built our ball wall / marble run, my goal was to have a flexible design so the pieces could also be used for water play and for a sensory table. With this week’s nice weather, we were able to test the theory, and it was a great success in terms of fun!

You can see there is some leaking that happens around the joints when two same-dimension connectors or pipes are next to each other (which was fine with my son – he liked that there was water coming out everywhere), but probably 50 – 60% of the volume of the water made it all the way through the maze.

The water works work better when you pour slowly, but my son liked the splash effect he got from pouring quickly.

The end point of our water maze was a plastic cup with two magnets glued on it. Whenever it filled up, we replaced it with the other cup, and poured the captured water back through the maze – we also had a tub full of water nearby.

The best part: when the cup fills up all the way with water, the weight is more than the magnets can support, so it slides to the ground. “Level complete!”

DIY Ball Wall

35 Replies

marble run

The theme for this week’s Inventors’ Lab was gravity, so I made a ball wall (aka marble run). This is like those exhibits you find in most children’s museums where where are pipes and joints mounted on magnets. The children can re-arrange them to make any path they choose, then run a marble through them to test their path. They may find that the ball shoots off-course at some point, and need to re-adjust the pipes for the ball to reach its goal. Just playing with these is a great exercise in tinkering and hands-on engineering. My son can play with these for hours, so we decided to make one for home and for class.

I got my original idea from Frugal Fun for Boys.

This was a really easy project once I got the supplies. About three-quarters of the effort was deciding which supplies to buy in what size (and what strength of magnets), so down below, I’ll include my full list, with affiliate links, and the lessons I learned to hopefully make your life easier if you want to replicate. In class, the kids definitely had fun with it!

Note: This marble run is designed for repeated use by lots of kids. I will also be adapting parts of it as the year goes on for water play and sensory play. There are lots of easier / cheaper ways to build a marble run for short term use at home, so I’ll include links to those at the bottom.

Ball wall

Supply List

On Frugal Fun she used regular size marbles, so I needed to adapt her materials a little. In our class, we have children as young as 2.5, so I wanted to use the bigger shooter marbles instead to make them less swallowable.

The materials I used: oil drip pans, 1 1/4 inch PVC joints (45 and 90 degree elbows), 1 1/4 inch PVC pipe, 1 1/4 inch OD clear polycarbonate tubing, a tube with a curved end – it’s part of a p-trap (you can buy the piece separately but I don’t know what it’s called), ceramic magnets, glue, shooter marbles, miscellaneous funnels 1, 2, 3 And a couple dinosaur party cups to catch the balls at the end of the run.

Technical notes / things I learned in the tinkering process

Pipes and joints: Important lesson – 1 1/4 inch PVC pipes are not 1.25 inches around! I think that’s their inside diameter. Outside diameter is 1.66 inches. These pipes and joints are bigger than you need for shooter marbles, You could go down one size, I think. The marbles run just fine through the clear tubing, which has an outside diameter of 1.25 inches, inner diameter of 1 1/8.

Marbles: I liked these shooter marbles (Note: don’t order these… they are regular small marbles, not shooters, despite the description) I also made marble size balls from Model Magic clay, which seemed like a fine idea in advance. They were pretty, they ran through the tubes just fine, and since they were lighter weight, they didn’t knock the tubes out of line as much. But, there were a couple problems. 1) If you mixed them with the marbles, the marbles were heavy enough that if they fell on top of a model magic ball, they’d squish it out of its nice round shape, and then it would start getting caught in tubes. 2) if you step on the model magic balls, they squish flat, and 3) after this accidental discovery, a certain three year old in the class took great pleasure is stepping on all the balls and squishing them flat. If you squish them once or twice, I can re-roll them into a round ball, but after that, they’re pretty much useless.

Funnels: I ordered the widest mouth funnels I could find, but none of these funnels had a wide enough neck for the shooter marble to go through… I sawed the end off the yellow one so a marble would go through, then I taped it to a pipe because at that time I didn’t have a file to file off the rough edges of the cut.)

Magnets: I wanted some that were strong enough that the pipes wouldn’t slip out of place every time you sent a marble through. But, they couldn’t be too strong, as I wanted it to be possible for a three year old to pull the pipe off the metal pan and move it around. The magnets I ordered (linked above) are perfect. I put one on the back of each 45 degree joint, 2 on the back of most items, and three on the 2′ long segment of PVC.

One issue I hadn’t foreseen is that you can’t just lean the pans up against a wall and let the kids play. The first time they grab hold of a pipe to pull it off the metal pan, the metal pan would fall on their head. I could try to teach them to brace with one hand and pull with the other – but that’s not really gonna happen. So, you have to secure the pan. Lots of Pinterest folks who use drip pans for magnet activities mount them on their wall permanently (putting screws through them into the wall) or semi-permanently by putting wide velcro strips on the wall. Neither was an option for me in my classroom, so I used ratchet straps to tie them to a bookcase. The only problem was then you have straps going across the front of the pan. I’m betting you could also use bungee cords… there’s enough of a rim around the pans that the bungee cord could hook to it. But since bungees come in specific lengths, you’d have to know in advance what length you needed.

Or, for home use, don’t buy a drip pan. You can just use your refrigerator to mount your ball wall… just be sure that the marbles can’t roll under the fridge.

This was a very quick and easy project, except for sawing the PVC pipe and clear tubes into the lengths I wanted. Using a hack saw and files to smooth the rough edges was perfectly do-able, but took 15 – 20 minutes per cut, I would guess. Then I learned about Ratcheting PVC Cutters which make the job SO MUCH EASIER!!!

I have also bought some flexible tubing and some T-joints, and plan to experiment with using these items in a water wall and for sensory table play, with either rice or beans.

Easier ways to do a ball wall, and other ideas

Use toilet paper tubes, paper towel tubes and masking tape like Lemon Lime Adventures and Tinkerlab.

Or those same tubes and magnets, like Growing a Jeweled Rose or Teach Preschool.

Or water bottles and magnets, mounted on the fridge instead of a drip pan.

Build a hand-held marble maze in a shoe box lid with craft sticks.

Here’s a collection of links to good options, both DIY and store-bought.

Resource for STEM activities

If you’re looking for 100’s of ideas for hands-on activities to teach science, engineering, and math, check out my other blog, www.InventorsOfTomorrow.com.

Building a mini submarine

9 Replies

A few weeks ago at our Family Inventors Lab, we studied submarines, and our book for the day was Papa’s Mechanical Fish, a really well-written and enjoyable book that shares the adventures of a family where the father is an inventor, who is sometimes successful and sometimes not. He is inspired to make a mechanical fish, and after several failed attempts makes a submarine the whole family can ride in.

At class that day, our main tinkering activity was to make a water-tight mini submarine that would keep a little paper person dry inside for 20 seconds underwater. Our supplies included plastic easter eggs, miscellaneous plastic containers, and tools that would help to waterproof things (tape, plastic bags, silly putty, things to wrap objects in, etc.)

This activity did what we hope to do with all our activities… it adapts to various ages and it teaches kids to experiment and adapt their efforts till they succeed.

Our littlest kids (2 – 3 year olds) mostly just used this as a sensory tub. They played with whatever was floating in the water.

Some of the middle-sized kids (3 – 4 year olds) did things like float an easter egg inside a plastic bowl boat or fill plastic Ziploc bags with water and float those.

Our next oldest (4 – 5) tested the other containers: water bottles, small food containers, and some travel-size toiletry bottles to see which would keep a paper person dry. Some would and some wouldn’t. They also tried wrapping the eggs in various things (paper, cloth napkins, plastic bags) to see if they would stay dry. All of those failed, except sealing the egg inside a ziploc.

The oldest kids (6 and 7) did the full tinkering activity with the easter eggs. Testing, diagnosing, hypothesizing, building a prototype, testing again, and repeating till we got it right. We learned that plastic easter eggs leak water because they have holes in the ends. We tried taping the holes and sealing the gaps with play-dough or silly putty. But even after you seal the holes, there’s a gap around where the two halves come together, and the eggs still leak. (And play dough makes a big mess when it gets wet!)

We eventually discovered a working solution: seal the ends of the eggs with silly putty. Put the paper person in. Wrap a silly putty seal all around the gap where the two halves of the egg come together. Submerge it. Count to 30. Bring it out of the water, dry it off, open it up, and Voila! we had created an easter egg submarine.

This is a great activity to repeat at home during bath time. Just grab a wide variety of plastic containers with lids from your kitchen, tear up some paper from the recycling bin to be your “people” you’re trying to keep dry, and head for the bath tub. Your child will learn about sinking, floating, water-tight vs. leaking, and the fact that bubbles coming up from your submarine is a bad sign… if air comes out, water will go in!

Building a Wind Tube

23 Replies

For our Family Inventors’ Lab class (a STEM class for preschool and kindergarten age), we have built a fun tool, which encourages the kids to tinker – see my last post for how kids play with a wind tube. This post is about the tinkering process we used to build and refine our DIY wind tube.

Supplies

We started with the directions from Exploratorium. We ordered from Amazon:

- a big, powerful fan – we use the Honeywell HF-910 Turbo Force. (My colleagues tried using a smaller Honeywell, and smaller hoops to save money, and their version can just barely lift a scarf up and out of the tube. It’s just not nearly as fun.) The HF-910 is no longer available but the Air Monster and the Comfort Zone Powrcurve look like they’d work. You need a big fan that can be tilted so it’s horizontal to the floor.
- TWO 14″ embroidery/quilting hoops and
- an acetate sheet Ours is 40″ tall. It comes in a 12 foot roll, you’ll only need about 4 feet of it. Exploratorium’s directions called for .0075 ml thickness, we used .01. It’s a little pricier but it’s been very durable which is important to us because we transport it to several sites and has survived ten years of small children banging on it. (Other builders have used 1/32″ thick polycarbonate, but I haven’t found that in large sheets.)
- spacers – see below

Assembly

We cut the acetate sheet, rolled it to make a tube, and assembled the tube with the hoops. Definitely a two person job. You can clamp the plastic between the inner and outer layer of the hoop, just like you would fabric. We then used clear packing tape to tape the seam. (We also taped over the metal clamps on the hoops, and the edges of the acetate sheet on one end, just so kids wouldn’t scrape themselves while playing.)

Spacers

You need spacers to lift the tube up off the fan. Exploratorium recommends wooden spacers that you cut a notch in. We built spacers with Duplos and set the tube on those. (You can see them in the videos in this post.) For our family, that worked fine, because it was easy to rebuild them if they got knocked off. For class, I wanted something I didn’t have to rebuild. I found some giant clothespins, which worked great. (You can find 6″ or 9″ options. Nine is better.)

For kids over age 5 or so, that’s all you need. You just set the tube on top of the fan, and you’re fine. They may knock it off a couple times, but quickly learn to be more careful. If it does get knocked off and lands on someone’s head, it’s startling but does not hurt.

Tie the Tube Down?

For kids under 5, you’ll want to tie the tube to the fan so it doesn’t get knocked off as much. Exploratorium recommended drilling holes in the spacers, disassembling the fan, and fastening the spacers on with zip ties. We decided it would be much easier to just thread pipe cleaners through the springs on the clothes pins, and loop those down under the fan and back up again (no dis-assembly required) and twist together to tighten. It was easy to do, worked great to tie them down, and is easy to undo later if desired. An advantage to the clothes pins is that it’s easy to clamp the tube onto the fan, then easy to un-clamp it for transport.

Cover with Mesh?

If you will be using the tube with young children, be aware that they may try to put small items into the fan openings (beans, coins, toys, etc.) I usually avoid this issue by putting the wind tube in a hallway or in a large motor play area where there just aren’t any small items to put in. But, if you’re in a classroom full of small smare parts, you may want to cover the fan so they can’t drop things into it. I bought 1.5 yards of black tulle with pretty sparkles (like this), and we wrapped it over the fan, tying it off below with a twisted pipe cleaner. The tulle does work great as safety proofing and looks fine, but it definitely does diffuse the air flow from the fan, so some of the heavier things that would fly without the mesh on just don’t fly well with the mesh on.

Play Value

I’ve watched countless children age 1 – 10 play with this for hours. The under-one-year olds love just watching things fly up and out of the tube. The two-year-olds love shoving things into the tube and watching them fly. The three-year-olds start to make observations on which items flew best. The four-and-ups experiment with building things, tying things together, trying to put things in from the top, and so on. Some of the parents get caught into the experimenting too, folding paper helicopters and such to test what will fly. The kids play really well together – part of the point of this game is to put something in and LET GO, so there aren’t many issues with having to share something that someone was holding on tight to. They all play happily side by side. They don’t really need to take turns, as it works fine to have four or five things flying at the same time. Here’s some of the items we have launched: scarves, ribbons, pipe cleaners twisted into spirals, dixie cups, plastic dishes, and paper cut into a variety of shapes. (See more video in my Wind Tube post.) I have also flown silk leaves for a fall theme, felt snowflakes in the winter. Toy parachutes are also great – if there’s ANY chance the plastic paratrooper will get caught in the fan, just cut him off and use the parachute alone.

Alternatives to our DIY wind tube

There is a DIY wind tube tutorial on Instructables. It requires that you own real tools, which I don’t. 🙂 babbledabbledo describes building a simple “vortex” by just rolling a tube of poster board and setting it directly on the fan. Kids put a scarf or a balloon above the tube where it gets caught up in the rush of air. Super simple! I like that with our tube, the kids can put the item in at the bottom and see it travel up the tube, but this simple alternative may meet your needs just as well Kodo Kids makes a wind tunnel that looks fabulous! And I know their materials are very high quality. I’d love to have it, but it costs $499 plus a $50 fan, versus the materials for my DIY tube are around $176 before tax. [Fan ~$55; hoops $20; acetate sheet $82; clothespins $19; optional tulle fabric.] Or you can buy the science museum version for $13,500. For lots of ideas for STEM enrichment activities with kids, check out my blog www.InventorsOfTomorrow.com.

More Good Days with Kids

Research, Resources & Realistic Recommendations for Parents of Kids age 1 to 7