Category Archives: Engineering Challenge

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.

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.

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.


Engineering Challenge: Building Bridges

Building a bridgeOur kids’ engineering challenge this month was to build a bridge that spanned one of the library’s delivery boxes and would support the weight of a bottle of paint. Before we started building we talked about the three major types of bridges, the truss bridge, the suspension bridge, and the beam bridge. I then reinforced the engineering process, and that re-designing and trying again are important components.

A bridge made of stringFor supplies I provided pipe cleaners, popsicle sticks, string, newspapers, masking tape, straws, and scissors. Our first level of challenge was to build a bridge over the short section of the box. The second level of challenge was to build a longer bridge over the long dimension. The third challenge was to remove one of the materials they were using, so build without straws or without pipe cleaners. Only two of the children took me up on the third challenge, the rest wanted to free build and improve their existing bridges once they had passed the first two challenges. Adding extra paint bottles was a common self-imposed challenge.

Bridge built of popsicle sticks and stringIf I had been building a bridge, I would have used rolled up newspapers to make a beam bridge, but no one tried that. The most popular design choice was essentially a suspension bridge, with string or pipe cleaners attached to each side of the box. This still left a lot of room for individual creation, and while there were a lot of variations on that theme, none of them were duplicates. Interestingly, as far as I can tell none of the children were influenced by the work of others. This was simply a popular design.

Engineering Challenge: Newspaper Structures

A girl kneels in the newspaper structure she builtFor this Engineering Challenge we built structures that were large enough to fit inside using nothing but newspaper and masking tape. The structures had to be free standing, but did not need to have walls, floors, or a roof.

Before the program started, we talked a

little bit about  the shapes that make for a stable structure. Some of the children had participated in a previous building workshop and remembered that triangles are excellent

 weight bearing shapes. We also talked about different ways to use the newspaper, including folding, rolling, various rolling techniques, and other ways to build with newspaper. I let the children know that “fit inside” could mean a lot of different things: standing, sitting, lying down or anything in between. Each position would bring its own set of challenges.

There was a lot of parent-child interaction, and a lot more child-child grouping for this project than for some of our previous Engineering Challenges, which made for a loud and boisterous time, but also created some great conversations about material properties, physics, engineering, and the building process.

A family fits inside their newspaper structureFor our previous challenges I had set up multiple levels of challenge so that even if someone was successful immediately, they could still remain engaged in the process. For this program, however, the second levels of challenge were essentially unneeded. The time it took to roll the newspapers, plus the inherent difficulty of the challenge and the general need for most of the participants to try several ideas meant that almost everyone required the entire hour to simply complete their project. I suspect some of our younger participants would have needed a lot more time if they had not been partnered with an older friend or had help from a parent. We had one family of young children that was kept busy the entire time building as a team with their parents so that the entire family could fit inside their structure! The little kids worked to roll the newspaper, while the older children and parents designed the structure and figure out the best way to implement their design.

A girl lies in the newspaper structure she built

The level of engagement in the room was extremely high. They were all determined to make their structure the best possible, despite the difficulty of the challenge. I was a little worried that the frustration level would be high, but I was pleasantly surprised to see how willing the students were to recognize that something wasn’t working, analyze why, and then try again with a modified strategy.

Engineering Challenge: Sails


Our first Engineering Challenge for kids got off to a fabulous start with a program about designing sails. I had experienced this activity for myself at conference on science education, where it was presented by members of the Boston Museum of Science team for Engineering is Elementary. This activity is lesson 3 of their Catching Wind unit.

For a setup I built a “boat” out of a piece of styrofoam and taped drinking straws underneath it. I then strung fishing wire through the straws and taped the fishing wire between two tables. This created a stable boat that would slide along the fishingline. I made two small holes in the middle of the boat just large enough to stick a popsicle stick into. The original program instructions suggest creating only one hole so that the popsicle stick can only be inserted facing in one orientation, but the styrofoam was flexible enough that I felt comfortable making two holes so that the stick could face either direction. This seems like a lot of setup when you could just put boats in water, but there’s a method to the madness. By creating a very prescribed boat scenario, we cut down on a lot of variables. The boat can’t go sideways, or have a piece fall off, or catch the wind at a slightly different angle every time. The only thing that will change from trial to trial is the design of the sail, thus reinforcing that child designer is in complete control of what is going on.

OLYMPUS DIGITAL CAMERABefore the program started I cut small squares out of each of our materials which included tin foil, felt, wax paper, tissue paper, and construction paper. I gave each child a package with these small pieces and we examined them together as a group, discussing their properties and how those properties might affect its usefulness as a sail. Providing trial samples of the materials instead of examining the large pieces we intended to use for actual construction was suggested by the Engineering is Elementary team to help allow the children to explore the materials without getting distracted by trying to jumpstart the building process or possibly ruin fragile materials like tin foil by exploring the range of possibilities the materials present.

After walking through an exploration of the materials, we talked about sails, sailboats, windmills, and what factors we thought might be important to catching the wind. After about fifteen minutes we were finally ready to start building. I handed out the sail materials, markers, masking tape, and popsicle sticks and the children got busy.

OLYMPUS DIGITAL CAMERAThere was quite a wide range of ages for the program. The original challenge, simply get the boat to sail from one side to the other was a struggle for some of the younger children, while the older kids were able to design an efficient sail almost immediately. I encouraged everyone, even those who had been successful, to go back and redesign their sail to see if they could make it even better. One of the teen boys asked how we’d know if they’d made it better, and I suggested using speed to determine success. I ran upstairs and got my stopwatch so that the students could compare their first boat and second boat.

OLYMPUS DIGITAL CAMERATiming the boats turned out to be a great idea. The noncompetitive kids were so engrossed in their own work that they barely noticed that other kids were also timing their boats. But there was also a large section of kids who quickly turned it into a friendly contest, designing and redesigning over and over again to shave a second or two off of their best time. I had been encouraging parents to participate, and now that there was a competition aspect, I had whole families competing with each other to see if Mom or Dad could build a faster boat than their child. My favorite was a family with boys about 8 and 12. When their older teenage brother came to see if they were ready to go, he got sucked into trying to beat his younger brothers. Then the grandfather came down to see what was taking so long, and he challenged the whole family that if they could beat the boat he was going to build he’d take them all out for ice cream. The boys won.