Engineering Challenge: Ping Pong Ball Zip Lines

OLYMPUS DIGITAL CAMERAFor our March Engineering Challenge we built devices that would carry a ping pong ball down a piece of fishing line. I got the original idea from  a PBS Kids Design Squad activity, which I then adapted a bit for a wider age range.  The original challenge suggested using 4-5 feet of fishing line, as less was too short and more was likely to sag. I didn’t measure exactly, but I know the width of the stage area in our meeting room is about as wide as I am tall, which makes it roughly 5 feet.

The children were given straws, pipe cleaners, paper clips, egg cartons, spoons, washers, paper, and tape. The initial challenge was simply to build something that would carry the ping pong ball down to the bottom of the line. I had a whole “and the stage is made of pingpong lava, that doesn’t hurt you, but will burn up your pingpong ball!” story to help forestall the inevitable wise-guy just letting the ball fall and bounce to the end of the stage. My audience skewed younger – of the 30+ kids, I’d say at least 20 appeared to be 8 or younger – and they really bought into the lava story with enthusiasm.

With my engineering challenges I like to have multiple levels of challenge. Once a child has completed the first level, I give OLYMPUS DIGITAL CAMERAhim or her the second challenge. This way I can differentiate everyone’s experience, allowing everyone to walk away feeling successful. Some kids will only complete the first level, other kids will complete several. For this challenge, the second level was supposed to be similar to the PBS Design Squad rules, which was to make the ping pong ball travel to the bottom in less than 4 seconds. However, I ran into a problem, in that all of the vehicles managed to do this on the first build, essentially erasing it as a challenge.

At first, I thought perhaps the lines were not at the right angle. The original challenge also suggested an angle of about 30 degrees. Re-evaluating the lines, I decided they were probably more like 45 degrees. I lowered two of the four lines to be closer to 30 degrees, but that didn’t seem to make much of a difference. I decided to change the second challenge to be to see how slowly you could make the ping pong ball go down the line.

OLYMPUS DIGITAL CAMERAThe older kids seemed to really get into the challenge of making it go slowly, and were pleased with their results. At the beginning of the event, I had emphasized that the Engineering Process involves constantly testing your design and then going back to improve it. I was trying to forestall frustration in what I had initially deemed to be a true challenge for the younger-than-average audience, but apparently the kids took the message to heart. Despite the fact that it actually ended up being a fairly straight-forward challenge, many of the children went back and redesigned their vehicles, even after meeting with success, so that they could “be the best possible.” Some of the children spent a lot of time each designing several separate vehicles using different materials so that they could determine which one worked the best. Most of the children were so caught up on redesigning and recreating that they never came to me for a second level of challenge, but that was more than okay, as the point of the exercise was to have fun, feel confident about building things, and walk away thinking like an engineer, all of which were clearly accomplished.

Engineering Challenge: Roller Coasters

Roller coaster engineering challengeOur January Engineering Challenge theme was roller coasters. Before we started, I talked a little bit about momentum, demonstrating that a marble rolled along a mostly flat track will stop, but a marble rolled down an inclined track will keep going, and that marble rolled down a very steep track can build up enough momentum to keep going even uphill. Most of the children nodded along, as this was all well within their life experience of how balls interact with the world.

Once they had the general idea, I gave them the first challenge: to build a roller coaster that allowed the marble to go up and over a hill. I purposefully make my first level of challenge relatively simple so that every child participating will have at least one success by the end of the program. To accomplish their challenge the children were given pipe foam that I had cut in half lengthwise, forming a channelled track. The pipe foam was perfect for our purposes: very flexible for young hands to manipulate and very cheap at at about $1 for a 6 ft tube, which provided 2 channels. I also gave them access to lots of tape. I had regular masking tape and also painter’s tape, which I Roller coaster engineering challengeemphasized needed to be used if the children were going to use the wall as part of their building process. (And here I’d like to put in a plug for painter’s tape. It’s more expensive than regular masking tape, but otherwise so much better! Unlike masking tape it never takes the paint off the walls. It’s also much easier to peel off the roll, a problem we’ve had with several different brands of masking tape. It’s almost as sticky as masking tape, and I’ve successfully used it to hold posters up on the wall for as long as I wanted the poster to stay up.)

We had about thirty kids working on the challenge, mostly in small groups and pairs. There were a significant number of dads with their children, which is always exciting to see. I love watching the parents get involved with the engineering, and the great discussions the parent/child interactions produce. The kids are often more accurate in their predictions of what will happen! Maybe because they have spent more time messing around with similar materials?

An engineering challenge roller coaster Our second level of challenge was to create a loop-the-loop. This was significantly harder, but everyone got there eventually. I like to emphasize that engineering requires a lot of trial and error. I did not see any frustration, all of the participants were confident that just one more tweak to the design would yield results.

I told the children who completed the second challenge that they could either do a free design, or they could try for two loop-the-loops. Most chose to try for two loops. One thing I noticed during this program was that it was not enough for the children to accomplish the task: they needed me to be a witness to their success. This meant running around the room quite a bit so that I could personally watch marbles rolling around the tracks. The looks of delight were definitely worth it.

Science Storytime: Marble Runs

Marble RunI had all of the supplies to make marble runs as part of a school-aged Engineering Challenge, and I thought my younger Science Storytime preschool friends would also like to experiment with the supplies.  Unsurprisingly, I was correct.


To begin we talked about hills and rollercoasters, trying to elicit from the children their life experiences with how things roll. They were eager to let me know that balls roll down a hill, and that they do not roll up a hill. There was some excitement when I used a marble run to show that if enough momentum can be built up, the marble will roll uphill. I demonstrated this several times, with lots of thinking out loud and experimenting with how steep the angle of the run needed to be before the ball would go over a small hump, to make sure that the students understood Marble Run experimentsthe basic idea. Then I handed out marbles and pipe foam that had been cut in half, along with our ever-present painter’s tape, and let the children experiment on their own.

As usual, the range of exploration was wide. Some of the younger children were happily entertained for a very long time simply rolling marbles down a track. A few of the parents wanted to move on to more complicated designs. I wish that I had made it more clear that, especially for young preschoolers, just interacting with the materials is a learning experience all in itself. Rolling the ball down the track repeatedly is building up a schema of how the world works that will be helpful to that child later, even if it’s not the sort of “experimenting” that we’d pictured beforehand.

Experimenting with marble runsSome of the children added the toys that were already in our playroom to their marble runs. Of particular interest were the buckets we keep smaller toys in. Several children wanted to set their marble runs up so that the marbles would land in the bucket. (I wish I’d thought of that ahead of time, because once this idea caught on it definitely made containing the marbles rolling all over the floor much easier.) Other children used the buckets as ramps in their building process. Another child spent a lot of time with a school bus, first figuring out how to get the marble to roll through the bus (harder than it sounds when you’re quite small and the materials barely fit) and then using it as a base for a loop-the-loop that was her own self-initiated challenge.


Science Storytime: Paper Tools

paper craftWhile we call it Science Storytime to help easily market it to the target audience, the program is really a STEM Storytime. Today’s theme was focused on the T: Technology. We wanted the children to explore the tools and technology of paper crafting. The nature of the activity meant that this became a STEAM (Science, Technology, Engineering, Arts, and Math) program. The great part is that I really did hear every part of the acronym being mentioned! We talked about how paper is made (appled Science), we used tools (Technology), some of the children made 3-D art (Engineering), the craft aspect was obviously Art, and Math was covered when I heard some parents say things like “oh, you made a pattern” or “which piece of paper is bigger?”.

We were supposed to start the program by reading Trees to Paper, part of the Rookie Read About Science series. I love paper craftthose books because while I think they were intended to be for beginning readers, the simple sentences and basic explanations generally make them perfect for sharing with preschoolers. Unfortunately, and embarassingly, I had brought the book home to share with my own preschooler, and forgot to bring it back to the library. So instead we just jumped right in. I talked very briefly about how paper is made, but since I could see my young audience was restless and very distracted by the array of fun materials on the table, I kept it to only a few sentences. Next, I demonstrated how to use my paper tools, such as a stapler, hole punch, tape, or scissors. Most of the children had not seen a scrapbooking hole punch before, and there were some gasps of amazement when I punched out a large star, which I hadn’t been expecting.

Finally, I brought the children over to the table, and told them they could explore the materials however they wanted. “I can do whatever I want with this paper,” one boy kept repeating, so clearly I struck a nerve there. I emphasized to the parents that since the children were exploring the tools, there was no wrong way to use them. If they wanted to do nothing but punch holes, or staple and then remove the staples immediately, that was fine.

cutting with scissorsFor most the children, they were thrilled with the opportunity to use tools that may have been off-limits or never introduced. The staplers were very popular, as were the tape dispensers. I suspect that these are items many children have been told not to play with before. But I had plenty of tape and staples, so it was not “going to waste.” The hole punches were, unsurprisingly, also very popular, especially after they realized how useful the punched out shapes could be.

The range of scissors cutting was wide, from proficient to emergent to essentially nonexistant (I heard one parent ask, “Have you ever used scissors before?” in all sincerity). Everyone tried cutting to the best of their ability, and seemed to be happy with their results.

Science Storytime: Static Electricity

Static Electricity GhostThe effects of static electricity are visually stunning and a very common life experience so I knew that I wanted to use it as a theme for Science Storytime. I wasn’t able to find a book for preschoolers that went along with the theme, so we started with a simple discussion of static electricity. Many children identified with getting shocked after sliding at the playground, or having their hair stick up when taking off a hat. I talked a little about how things can get charged in a very simple way, using my hands to represent a charge (closed fist) and a noncharge (open palm) and how they fit together. Then I demonstrated with a balloon and some tissue paper. In addition to watching the tissue paper stick to the upside down balloon, I had also made a ghost out of tissue paper, and used the static charge to make the ghost dance around and haunt the room without even touching the balloon.

static electricity and hairNext, I talked about when two charges try to touch each other, punching my fists together to show that they didn’t fit. I had a charged piece of plastic, and when I tried to put it near my charged balloon instead of sticking together, the balloon’s charge made the plastic move in the opposite direction. Apparently you can even get rings of plastic to levitate! I couldn’t perfect my technique in time, so I had to settle for simply watching the plastic be repulsed by the balloon, which was still pretty impressive. The kids seemed to appreciate my silly “get away from me!” voiceovers.

decorating a balloonAfter I had demonstrated static electricity to the group, I let them all sit at the table with their own balloons, pieces of cloth, and various things that could stick. I think I should have been more explicit, or perhaps simply repeated it more often, about the fact that I was using the cloth to charge up my balloon, because several of the children seemed to have missed that fact and were confused about how to charge their balloons.  The WonderWorks program had mentioned cutting feathers so that the bits would jump onto the balloon, and the parents were quite impressed, but none of the children seemed to be inspired by that particular idea. There was lots of balloons sticking to hair, and to the feathers, yarn, and tissue paper I had put out. I had set out tissue paper butterflies stapled to cardboard so that the children could use their charged balloons to make the butterflies’ wings flap. I also put out markers so that they decorate their butterfly, since I generally have one or two kids who want a physical product to take home with them. In the nature of programs taking an unexpected turn, the children were all interested in decorating their balloons with the markers, which probably shouldn’t have surprised me, including some who made faces and then used static electricity to stick yarn on as hair.

Engineering Challenge: Hurricane Towers

OLYMPUS DIGITAL CAMERAI was originally inspired by this write up of Hurricane Towers, which was based on a NASA lesson plan. After reading through all of the NASA information, I decided that my target audience was a little too wide in age to have a lot of rules, so I simplified the activity somewhat. (Generally at these programs my students will range from about five to twelve, with even younger siblings often “helping”.) I like to give multiple levels of challenge during my engineering activities, that way every child walks away from the program having been successful at completing at least one level, yet more sophisticated students are still challenged. The first level of challenge for this project was to construct a tower in which the tennis ball was not touching the ground – OLYMPUS DIGITAL CAMERAdefined as my being able to see air between the tennis ball and the ground.  The students were given tape, pipe cleaners, paper plates, straws, popsicle sticks, yarn, and paper clips to work with. Some students made actual towers, others had barely the width of a straw between the ball and the table. One team of siblings decided to use the edge of the stage, and since I like to encourage creative thinking, I declared that since the only rule was that it had to have air space, I didn’t mind. All were deemed successful.

TowerThe next level of challenge was to have the tower survive a “hurricane” – otherwise known as my high-powered fan. I had done a test run of this activity a few days before with my homeschooling group and discovered that when I tried to use my fan to test the towers, every piece of  building equipment on the table  was blown around  – not to mention the projects that other children were workingtower on. Since I like to encourage the children to frequently test their projects to see if they need any design changes, that quickly became a problem. To try to overcome this, I had the students build their towers on top of paper plates that could then be moved to a separate testing space. However, I should have specified they use upside down paper plates, because the raised edge of the plates caught the wind from the fan and sent the projects flying. This was easily fixed by taping the edge of the paper plate to the table, but was an extra added step.

towerAll of the students were able to successfully build towers that withstood the fan, and with surprising ease. The towers were all very inventive. I love to see all the creative ways that the children come up with to solve the initial problem. It’s especially interesting to me to watch the different age ranges work out the logistics. I think it’s fascinating that older children tend to put a significantly longer amount of time into the planning process, and want to perfect every little bit of the tower before testing it, while younger children are more likely to just go with gut instinct – and were just as often successful.  I just wish I’d managed to get a picture of everyone’s tower. One group noticed that my large box of supplies that I’d used to carry the materials into the room had a box of marbles that I intend to use for a program later in the year, and they asked if they could use the marbles to weigh down their tower so that it wouldn’t blow away even without using tape to keep the paper plate on the table. I wanted to see what would happen, so I let them, and they were successful.

Science Storytime: Clouds

Clouds experimentInspired by the ALSC program about weather, this week’s Science Storytime theme was clouds. We read parts of Tomie DePaola’s book Clouds and talked about clouds in general, such as colors of clouds, when we see clouds, and other cloud experiences the children had had.

After discussing that all clouds are made of water vapor, but you need lots of heavy water droplets before it starts to rain, we used a model rain cloud for our activity. We put shaving cream on top of a cup of water to represent our cloud. Next we used pipettes to pour liquid water colors into the shaving cream. At first the shaving cream cloud simply held up the colored water. But eventually there was enough water that it had become heavy enough to “rain” into the bottom of the cup. The pictures I had seen online showed very distinct raindrops, but for us it was generally more of a seeping. The water under the shaving cream turned colors, so the “rain” was getting through, but only one cup seemed to have distinct raindrops. The children were so engaged with the rest of the activity that they did not seem to mind.

I made sure to verbalize that the activity had multiple levels of learning. Not only had we talked about clouds, but there was also a technology aspect to the program. Most of the children had not seen or used pipettes before, so figuring out how and when to squeeze was in itself entertaining. Since I set out multiple colors of water, color mixing and what happens when you combine various colors together inevitably became a part of the conversation as well. It was a very popular activity, and all of the children involved would have continued to interact with the materials for as long as I was willing.

I had wanted to make a cloud in a jar as I found online but I couldn’t get it to work with aerosol spray, so I had to nix that. It may have worked better with matches, but I wasn’t quite comfortable using matches in the library.

Science Storytime: Leaf Sorting

This was not one of my more successful Science Storytimes. The intention was to sort leaves by various attributes, as modeled so wonderfully here. However, it was a gorgeous fall day, and I only had two children come to the program, both very young (two and three, perhaps?). We read Counting on Fall and then talked about leaves a little. I passed out a bunch of leaves I had collected and the children happily began sorting them into piles based on color. However, since I’d expected more children, I had a LOT of leaves. In retrospect I should have only given each of the two children a handful, but instead I just split the pile in half. That meant that it took a fair amount of time to get through all of the leaves, and by the time they were done sorting by color, they had both more or less lost interest in the project and were asking to go play. I want the programs to be engaging, so once I realized I’d lost momentum, I just ended the program. I think the activity is still a good one, and next year I will try again. An older audience may have been more responsive, and less leaves per child would definitely have been more effective.

Engineering Challenge: Brushbots

BrushbotOur September Engineering Challenge was a bit of a departure from our previous challenges. Usually I try to keep the Engineering Challenge programs very open ended. I declare a goal, and then give the children supplies to achieve that goal in whatever manner they can think of. The Brushbots were much more “follow the directions” for the first half of the program, with creativity coming once the brushbot had been assembled and we were ready to decorate our creations. However, I thought that making little vibrating creatures was too appealing to pass up.

Brush BotTo make the brushbots I followed instructions found here, with the addition that we used two toothbrush heads instead of just one. One of the many websites about brushbots that I had looked at suggested that double heads made for more stable ‘bots, and a quick experiment convinced me that this was true.  Basically we cut the heads off of cheap toothbrushes, then used double sided mounting tape to both hold the two brush heads together and to create a sticky surface upon which to place the vibrating motor from a cell phone (available for about 75 cents on amazon). I had peeled the plastic back from the wires on the motor ahead of time, because I was worried that the students would snap the wires. On top of the exposed wire, we placed a coin battery. Since the wire was extending over the mounting tape, the coin battery just stuck to the tape. To make the creation vibrate, all we had to do was use a piece of clear tape to press the second wire onto the top of the battery. Peeling the tape off stopped the vibrating, creating a very simple on/off switch.

Brush botsNext was the fun part: decorating the brushbots. I did not get very many pictures, for a variety of reasons, and the ones I did manage to take are mostly blurry, but there was a lot of creativity on display. I had set out all the decorative elements I could find from my craft closet, including beads, pipe cleaners, tissue paper, plastic eggshells, tissue paper, googly eyes, and more. As a special added touch, I had a number of flashing LED diodes that were leftover from a previous project. Since we were already using batteries for the motors it was easy enough to attach the diodes to the battery. They were, not surprisingly, a big hit, with some brushbots sporting multiple batteries to accommodate the number of flashing lights.


Science Storytime: Surface Tension

Surface tension with Lego blocksFor our Science Storytime about surface tension I couldn’t figure out a good book to use for the subject, so we just skipped the reading section. We talked a little bit about surface tension, trying to tie it back to what we’d talked about when we discussed why bubbles are always round.  The science explanation was kept very short. I thought that this was one of those times where my very young audience was probably better served using this activity as a “what happens” experience rather than a “why is it happening” experience. Teaching science to young children can often get sidetracked by understanding the why of things, when preschoolers are still building up their understanding of  what is happening and how the world works in general.

For our first demonstration, I put Lego blocks in a tin of water and we looked at them floating around for a few moments. Then I added soap into the middle (thus breaking the surface tension of the water) and the blocks sprang to the edges of the bucket. The picture doesn’t really convey the process very well. I got the idea to use Lego blocks from this website.

Next we did an activity that my own preschooler never gets tired of. I poured milk into Surface tension demonstrationindividual tins for each child. We put drops of food coloring into the milk, then cotton swabs to dab soap onto food coloring. This caused the surface tension to break and the colors to swirl dramatically. The children were particularly taken with this activity and repeated it over and over, in some cases often enough that we needed to replace their milk so they could start over. Because the colors mix together, it also became a bonus lesson on color mixing. I have not tried doing this with liquid watercolors yet, but I need to attempt that, as I find liquid watercolors are so much easier to clean up and don’t stain your fingers.