He spent about 30 minutes working on it by himself using copper pennies and nails, but was still having some trouble. Seeing him working so hard, I got involved and decided to document the process. Hopefully, you can use what we learned to ensure success when you attempt this experiment with your own kids!

How Does It Work

I was actually surprised by how hard it was to figure out exactly how a lemon battery worked! There is a lot of conflicting and inaccurate information on the internet, but I found this document from the American Chemical Society to be the most helpful. It is easy to understand, detailed, and backed up by several other reputable sources.

The main information that I would want my child to know is that there are two sides to a battery. One side is called the cathode and that is the side that pulls electrons from the wire. The other side is the anode and that is the side that gives electrons to the wire. In my son’s Science is Weird class, the teacher used the metaphor of two women, Annie and Cathy, who were a giver and a taker. Annie would give you a kidney if you needed one. Cathy would take your kidney even if she already had two good ones. It would be really handy to remember if the cathode (the mean taker) was the negative side of the battery and the anode (the happy giver) was the positive side, but alas the opposite is true. For older children, if they remember Annie and Cathy, they can just remember that electrons, which are negatively charged, flow toward the positive side, so the cathode is positive.

Next, I would want them to know how these two sides of the battery can be used to power a device. First, they need to understand that electrons, which are negatively charged particles, will flow from the negative side to the positive side. This makes sense because the anode is giving electrons and the cathode is taking them. Because the electrons are flowing through the wire, electricity, which is essentially just moving electrons, is being produced. This electricity can be used to power a low-power device such as a small LED, a hand calculator, or a kitchen timer.

If you wanted to explain this even a step further, you could ask the question WHY is the anode the giver and the cathode the taker? This is due to the chemistry that happens inside the electrolyte, the electrically conductive substance that transports ions near the anode and the cathode. In our case, the electrolyte is lemon juice. The chemistry that is happening at the anode is that the lemon juice is dissolving the zinc off of the nail, which releases positively charged zinc ions into the juice and frees up electrons to travel through the wire. The chemistry that is happening at the cathode is that the electrons being collected from the wire are combined with positively charged hydrogen ions that the copper is pulling from the lemon juice. We didn’t see it, but this reaction produces hydrogen gas causing bubbles within the lemon juice. The anode is giving zinc ions to the electrolyte and giving electrons to the wire. The cathode is taking hydrogen ions from the electrolyte and taking electrons from the wire.

Troubleshooting Tips

My son read online that each lemon battery should produce about 0.7 Volts, so he calculated that he would need 3 lemons to produce the 2 V required for his LED. However, we found that when he was using pennies, the voltage they produced was inconsistent. I theorized that maybe since modern pennies are only coated in copper and not copper all the way through, imperfections in the surface such as nicks and scratches might be interfering with his results. To fix this we went to the hardware store and got 1 foot of copper wire. I believe it was gauge 8 AWG, but the thickness is not super important. The store was kind enough to strip off the plastic insulation for us and cut it into 4 pieces, though we could have done that at home using an exact-o knife and wire cutters. They also ended up giving it to us for free. These 4 pieces of copper were used as our cathodes, the positive end of our batteries that collects the electrons.

If I were to go back and do this experiment again, I probably would have cut a couple more pieces of copper wire giving us 5 or 6 cathodes instead of just 4. This would have allowed us to add more lemons to our battery circuit, which would have produced more voltage and would have caused our LED to light up even brighter than it did. As it was, with 4 batteries, it lit up, but it did not achieve full brightness.

Another suggestion if your battery is not working is to make sure that you roll the lemons to break up the little pouches of lemon juice inside it. The more juice is freed, the better able the lemon will be to dissolve the zinc off of the nail, freeing up more electrons. We used the galvanized nails we happened to have on hand, but bigger nails might produce a bigger voltage because they would have a larger surface area to dissolve zinc. This would allow our anode, the negative end of our battery, to provide even more electrons to the cathode.

Simple Lemon Battery Details

Recommended Age Range: Elementary
Time Required: about 15 minutes
Difficulty: Easy
Cost: Less than $7 in used supplies

Materials

• lemons (We used 4, but I recommend having 5 or 6 on hand.)
• galvanized nails (You need as many nails as you have lemons. We used 1.5″ nails we had on hand, but any outdoor nails will work. Bigger nails might actually work better.)
• copper wire (You need as many pieces as you have lemons, we used about 2.5″ pieces, but the length is not important. Again, I recommend having at least 5 or 6.)

Supplies

• alligator clips (you need one more alligator clip than the number of lemons)
• an led (or something to power…any device you have, such as a simple calculator or timer, that uses one AA or AAA battery will work)
• a voltmeter (optional, but it will let you measure how much voltage each lemon battery and the entire circuit is producing.)

Instructions

1. First, roll all of your lemons on the counter underneath your palm to free up the juice inside. The juice acts as the electrolyte that conducts electricity through the lemon.
2. Stick your copper piece (your cathode) and your galvanized nail (your anode) into a lemon on opposite sides. They should not be touching each other inside the lemon. To light up an LED, repeat this for 4 lemons.
   
3. Line up your lemons and connect the nail of one lemon to the copper piece of the next lemon using alligator clips.
   
4. Attach leads to the two end terminals. One lead should come off of the last piece of copper wire and one piece should come off of the nail on the other end. This open circuit is equivalent to a battery. It is ready to be hooked up to a device to power it.
   
5. Connect your LED! Of your mini calculator or kitchen timer or other device that requires just a little power. If it doesn’t work, try flipping the LED since they are designed to only work when the current flows in one direction. The shorter end should end up needing to be connected to the nail.
   
6. We did not do this step, but try adding an extra lemon into your circuit! Your light should shine even brighter! Also, if you got a kit of LEDs, try using different colors. Oddly, even though green LEDs were supposed to require more voltage, they lit up the brightest for us.
   
7. Optionally, if you have a voltmeter, try playing around with it and measuring the voltage between different points in your circuit. To get a reading, it needs to be set to the lowest number on the DC V setting. For our voltmeter that was 5, which means that full scale (if the needle moved all the way to the right) is 5 V. If your voltmeter does not seem to be measuring anything, try flipping the leads as it will only show positive voltage drops.
   

Have fun being an electrical engineer!

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Like the other “robots” on this site, this little spinning brushbot is not REALLY a robot, since it doesn’t have any sensors or respond to its environment. I’m still planning to get there sooner or later, so sign up for my newsletter if you’re interested in staying up-to-date!

The reason why I’ve held off on making a robot of this type before was because I didn’t trust my littlest munchkins not to eat the cell batteries. Combined with my constant vigilance during the construction process, I now have a crew that I am confident will survive the robot-making party we’re planning to have in the near future. If you have little kiddos, know that this project does contain choking hazards and use your best judgement!

Here is a short clip of my little brushbot in action!

Recommended Age Range: Kindergarten, Elementary, Middle School
Time Required: ~30 minutes
Difficulty: Easy
Cost: Less than $5 in used supplies to make one (The more you make, the cheaper the cost as buying in bulk saves a lot!)

Materials:

• toothbrusth (here’s the 50 pack we used if you have a big group)
• Mini vibration motor (This link is not exactly the same, but similar to what I used. You could also get a motor from inside a battery-powered electric toothbrush)
• Mounting tape
• 3V cell battery (This is a link for the 20 pack we used.)
• Googly eyes (mine are approximately 1/2″ or 12 mm, but came in a mixed size bag)

Supplies:

• Scissors
• Wire strippers
• Cutting pliers (or anything to cut the head off the toothbrush)

Instructions:

1. 1. Use the cutting pliers to cut the head off the toothbrush.

1. 1. Use your fingers to spread out the bristles. For improved stability, place a book on top of the toothbrush head with the bristles spread for several minutes (or as long as you wish).

1. 1. Use the wire stripper to expose about 1/4″ of wire on each of the leads coming from the motor.

1. 1. Cut a piece of mounting tape slightly smaller than a googly eye.

1. 1. Use the sticky side to attach one of the wires from the motor to the front of the cell battery in the location you would like to stick the googly eye.

1. 1. Peel off the backing and stick a googly eye on.
   2. Apply another piece of mounting tape for the second eye (without putting a wire under this side).

1. 1. Peel off backing and apply second googly eye.

1. 1. Use mounting tape to apply motor to toothbrush. It’s fun to experiment with the placement of the motor. Too far in one direction will cause the bot to tip over from being too heavy on one side. Too far in the other direction will cause it to spin so fast it eventually flips over. I found placing the motor approximately as shown worked pretty well. Make sure not to tape down the spinning part of the motor.

1. 1. Use another piece of mounting tape to attach the second wire to the opposite side of the battery. Note that at this point the motor will start spinning.

1. 1. Place another piece of mounting tape onto the non-spinning end of the motor and the front of the toothbrush. Peel off the backing.

1. 1. Peel the backing off the tape on the battery and attach it to the tape on the motor.

1. Put it down and watch it spin! (See video above.)

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Technically, none of these projects are actual robots, since they are unable to sense and respond to their environment. My kids still have a great time making and playing with them though, and little by little, we’re working our way there. One day, I fully intend to make a real (though probably very simple) robot using computer hardware.

I have several simple projects in mind before that though. I’m hoping soon to FINALLY use those solar garden lights I got from the 99 cent store over a year ago to power a project. Also, I’d love to devise a car, similar to this one, that uses a switch to automatically back up when it runs into something. (Baby steps!) If your child is also a robot enthusiast, sign up for my newsletter to stay tuned.

Watch below for a short clip of our simple homemade “robot” car in action!

Recommended Age Range: Kindergarten, Elementary, Middle School (younger kids will need adult supervision and assistance since this project uses hot glue)
Time Required: ~30 minutes
Difficulty: Easy to Moderate (need to get wheels glued on relatively straight)
Cost: Less than $8 in used supplies (Technically, we already had everything we needed after making our other bots, except the piece of foam. The dimensions aren’t critical, so you could probably fashion something out of packaging foam, but I bought a block from Walmart for about $1.) Buying in bulk reduces the cost per bot considerably.

Materials:

• A firm block of foam (we used a 6″ x 3″ x 2″ piece from Walmart for $1. This piece would provide enough for a dozen cars.)
• 4 bottle lids for wheels
• 2 straws
• 2 skewers
• a rubberband (it needs to be longer than the smallest dimension of your foam when pinched flat — 2″ in my case — so that when you stick it through the foam, it will protrude on both ends).
• 2 googly eyes (optional)
• a pipe cleaner for a mouth (optional)
• 2 AAA battery holder
• 2 AAA batteries
• 1.5-3 V DC Motor
• switch
• Insulated wire (I used 22 gauge, but it’s not really important. Only a short (about 4″) piece is needed.)

Supplies & Tools:

• Scissors
• Wire strippers
• Needle nose pliers
• Hot glue gun
• Ruler
• Pencil
• X-acto knife (for cutting eraser)
• Butter knife for cutting foam (could also use X-acto or other knife)

Instructions:

1. 1. You want to end up with 3 pieces of foam. I started off with a block that was 6″ long, 3″ wide, and 2″ thick. To start, I marked at 1 and 2 inches from the end along the long edge. This was in order to cut off two pieces that were each 3″ by 2″ by 1″.

1. 1. Cut off the pieces using a butter knife or some other tool. Ideally, the final dimensions will be 4″x3″x2″, 3″x2″x1″, and 3″x2″x1″. However, you are more than welcome to try any pieces of foam that you have. The considerations are that you want the car to be wide enough for stability and tall enough that the rubberband attached to the motor and axle will be taut. You also don’t want the entire car to be too big, otherwise it will be too heavy for the motor to move. Technically, I didn’t even need the second small piece of foam that is not holding up the motor. I just added it so that the eyes would be symmetric.

1. 1. Cut two straws slightly wider than the base of the car. They should be at least the length of the car plus about the width of each wheel (bottle cap/lid) on either end (in other words, the width of the car plus two times the width of the wheel). A little longer than that is fine.

1. 1. Next you want to mark the skewers such that they are a little bit longer than the length of the straws. (About the length of the straws plus enough to allow for a bead of hot glue on either end.) I cut the amount shown in the picture and ended up needing to trim the straw a little bit to allow room for the hot glue, but that worked out totally fine.

1. 1. Cut both skewers at the length marked to make two axles.

1. 1. Cut one of the straws in half.

1. 1. Hot glue the larger length of straw on one end of the base of your foam.

1. 1. Next, use a ruler to mark a point in the middle of the other end about 1″ from the end.

1. 1. As straight as possible, use a pencil to make a hole through the foam at this location.

1. 1. Glue the two smaller pieces of straw on either side of the hole.

1. 1. Use the pencil to push the rubberband through the hole.

1. 1. Make sure you choose a rubberband long enough that it will stick out on both end of foam at the same time.

1. 1. Next, use hot glue to attach a bottle cap to one end of each your two axles.

1. 1. Stick your axles through the straws. Make sure that one of them is threaded through the rubberband.

1. 1. Use hot glue to attach a bottle lid to the other end of each axle. This was probably the hardest step of the whole process for us, because first I accidentally touched the straw with the hot glue. I ended up trimming the straws on all 4 ends to give us a little more clearance for the hot glue. Also, you need to hold the bottle lid in place for a minute or so while it is drying to make sure that it doesn’t dry crooked.

1. 1. Next make the circuit that powers the motor. You will need to connect the motor, the battery pack and the switch. Technically, if you’re willing to pull the battery out each time, you don’t need a switch. However, if you are going to use the switch, you will need a third piece of wire to connect the motor to the switch. Start off by a piece about 4 inches long.

1. 1. You will need to strip the insulation off both ends of the piece of wire you just cut. Before you do this, you will need to make sure your wire strippers are set properly. Adjust the location of the screw until there is a small hole remaining when you close the wire strippers completely.

1. 1. Use the wire strippers to strip off about a quarter inch off each end of your short piece of wire. You may need to strip off insulation from the ends of the wires attached to your battery pack if necessary.

1. 1. Get your 3 components (battery pack, motor, and switch) ready to connect. For the most reliable connection, these components should all be soldered together. However, it works nearly as well for our purposes to just wrap the wire around the leads. This makes it a little more child-friendly than a hot soldering iron and also easier to disassemble for future projects.

1. 1. Connect all the components in a loop by wrapping the exposed metal of the battery pack leads to the motor and switch and using the piece of wire to attach the motor to the switch. I find it works best if I use the needle-nosed pliers to make a small hook in the end of the wire. After putting the hook through the hole in the connector, use the pliers to wrap the end of the wire around the connector.

1. 1. Once your circuit is made, insert some batteries and try flipping the switch to make sure it works. Provided it does, hot glue the battery pack onto the back of the car (the end that doesn’t have the rubberband).

1. 1. When you flip the switch, the motor will spin. The spinning motor will connect to the rubberband which will turn the axle which turns the wheels. It would be nice to know which way your motor is spinning so your car moves forwards and not backwards. I checked this by hooking the rubberband over the motor while I held the motor and turning the battery pack on and off to see which way the wheels turned. If the wheels turn the wrong way, just put the motor on the other side of the car. Once you know which side the motor should be on, hot glue the piece of foam onto the side that will hold up the battery. (If it’s hard to test while holding the motor, you can just glue on both pieces and test it in both spots before gluing it down. Also, note that if your rubberband is super stiff, you may need to cut down the length of your foam a bit. You want the rubberband to be taut, but it should not be super difficult to hook the rubberband over the motor shaft.)

1. 1. You want the shaft of the motor to be perpendicular to the rubberband (parallel to the floor). Since my leads stuck out a little bit, I used a pencil to dig out a little well to glue the motor into so that it would sit flat on top of the piece of foam directly over the rubberband.

1. 1. Glue the motor in place. At this point, it should be easy to confirm that you put the motor on the right side by hooking on the rubberband and turning on the switch.

1. 1. Even though my motor shaft was pretty flat, I still had a little trouble getting my rubberband to stay on when my car was driving. To fix this problem, I first cut off half of my pencil eraser using the x-acto knife.

1. 1. Then I used a skewer to poke a hole in the middle.

1. 1. Next I hooked the rubberband onto the motor and pushed on the eraser tip to keep it from falling off. Make sure that the rubberband is not twisted and is not rubbing against the foam at all. It should come up perfectly vertically through the hole before attaching to the motor.

1. 1. Next glue on the other piece of foam for symmetry, then glue the switch on top as shown. (Technically, you do not need this piece of form and could glue the switch somewhere else if desired.)

1. 1. Attach some googly eyes (totally optional!)

1. 1. Give him a pipe cleaner smile (or not! Completely up to you!)

You’re all done. Turn him on and watch him go! Ours was able to start moving on it’s own, though it wasn’t super fast. As you can see from our video above, with the added weight of my 4 year old’s small toy, it was no longer able to start moving on it’s own. However, with a little extra push to overcome static friction, it was on it’s way!

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This little car makes a great first electronics project for kids since they get to put together a simple circuit. Fortunately, it’s not very expensive, since we mostly used free, recycled parts like our deli meat container and bottle caps. Next I want to try to make something powered by solar panels from the 99 cent store instead of batteries. (Sign up for my newsletter to stay up to date.)

You can watch a video of our car in action below. Note that the way I hooked up the circuit, the fan pulled the car instead of pushed it. To get the car to move the opposite direction, you would just need to switch the leads on the motor. (Or you could make the car even more awesome by using a DPDT (double pole double throw) switch instead of the simple ON/OFF switch that we used. That would allow you to toggle the direction the car moved depending on which way you flipped the switch.)

Recommended Age Range: Kindergarten, Elementary, Middle School (younger kids will need adult supervision and assistance since this project uses hot glue)Time Required: ~30 minutes
Difficulty: Easy
Cost: Around $10 in used supplies (The propeller is the most expensive component. I bought 4 of the one listed below for $16 total though the price fluctuates. It was $3.10 per propeller plus around $3 shipping and handling for all 4, so there is definitely a benefit to buying in bulk. A different, less expensive propeller could be used as long as it has a 2 mm shaft hole diameter.)

Materials:

• Lightweight car body (we used a deli meat container, but you could also use a block of foam)
• 4 bottle lids for wheels
• 2 straws
• 2 skewers
• 1 popsicle stick (for mounting motor, not needed if you used a block of foam or something flat)
• propeller
• 2 AAA battery holder
• 2 AAA batteries
• 1.5-3 V DC Motor
• switch

(If the one I used is out of stock, these should work as well.)

• Short piece of wire (I used 22 gauge, but it’s not really important)

Supplies & Tools:

• Scissors
• Wire cutters
• Wire strippers
• Needle nose pliers
• Hot glue gun

Instructions:

1. First, cut the two straws so that you can attach the wheels to the bottom of the container. The length should be a little bit more than the length of the bottom of the container plus the width of the 2 wheels as shown. If you cut the straws too short, then the wheels might hit the container, which is not a major problem.



2. Hot glue the straws onto the bottom of the container.



3. Cut the skewers so that that they are slightly longer than the straws.



4. Hot glue a “wheel” onto one end of each skewer.



5. Thread the wheel plus skewer through the straws.



6. Hot glue the other wheel onto each skewer.



7. If needed, glue a popsicle stick or something flat onto the lid of the container to create a flat surface on which to mount the motor.



8. Next attach a lead from the battery pack to the switch. Ideally, the lead would be soldered to make a more permanent connection, but since I don’t want my kids around soldering irons at the moment, we just used needle-nosed pliers to wrap the wire around the post on the switch.



9. Attach the other lead from the battery pack to the motor.



10. Next, you need to make a little jumper wire to connect the switch to the motor and complete the circuit. Cut a piece of wire from your spool and strip off the ends using the wire strippers as shown. Depending on what type of wire strippers you have, you might need to adjust the screw on your wire strippers so that when they are closed, the hole is about the size of the internal wire.



11. Connect the short wire to the motor and switch making a triangle with your 3 components (battery, switch, motor).



12. Next push the propeller onto the motor shaft. Mine press fit snugly together, but if not, you can add a little hot glue. Just make sure not to get glue near where the shaft connect to the motor.
13. Glue the motor onto the top of the car, making sure not to cover any vents on the motor. You can also glue the switch and battery pack down, but it’s not really necessary.

Now all you have to do is insert batteries if you haven’t already and flip the switch to start the car. Note that if you used a toggle switch, you’ll be able to get the car to move forwards and backwards. If you didn’t use a toggle switch, which direction the car moves will depend on what direction the motor is spinning. My car moves toward the propeller. If I wanted it to move in the other direction instead, I would just need to switch the battery pack leads. However, I’m lazy and my kids didn’t seem to mind, so we left it as is.

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For the full, picture tutorial on how to assemble this game, check out my guest post on 123Homeschool4Me. Sadly, this will be my last post as the site’s science contributor as, happily, our family welcomed our fourth child (a sweet, healthy baby boy) earlier this month. If you’re looking for more fun, science-y projects to do with your kids this summer, be sure to check out all of my 123Homeschool4Me posts as well as the many science and engineering posts on this site.

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Recently, I was flipping through my son’s Waldorf first grade curriculum book and saw this weather vane project. It fit so perfectly with what my son was already studying that I decided to make one and feature it as my science contribution on 123Homeschool4Me this month. To make it a little more educational, we also made our own homemade compass to orient our weather vane. (See the 123Homeschool4Me post for detailed picture instructions for both activities.)

If you’re looking for a great, fun book to go along with your weather studies, particularly for younger kids, I highly recommend Freddy the Frogcaster. My 6 year old stumbled across this picture book at the library and he and my 4 year old really enjoyed it. (Apparently there are other books in the series featuring blizzards, tornadoes, and hurricanes. I need to remember to add them to my library hold list.) If you’re interested in a slightly less educational, but extremely fun book about weather, be sure to incorporate Cloudy with a Chance of Meatballs into your weather lessons. While it obviously doesn’t feature REAL weather, it is impressive how many weather-related terms and expressions have been fit into this book in the context of food.

Don’t forget, head on over to 123Homeschool4Me to find a full picture tutorial for making your own homemade weathervane and compass and have fun encouraging your budding meteorologists!

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Your kids can harness the power of electricity by putting together their own homemade batteries using items you almost certainly already have lying around your house (pennies, aluminum foil, paper towels, vinegar, and duct tape). They can then use their batteries to power an inexpensive LED. This activity is a great way to show kids in elementary and middle school how electrons moving through wires can power devices and get them thinking about the challenges involved in powering large devices. Hopefully this activity will also bring them a new appreciation for technology they use everyday from indoor lighting to smartphones.

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Like the wigglebot, the inspiration for this project came from the book, Robotics: Discover the Science and Technology of the Future. However, in that book, the power source was supposed to be a cheap solar panel. Well, we took the solar panel out of a solar lawn light from the 99 cent store, but when we were putting together our bot, we found that it wasn’t powerful enough to power the motor even in bright sunshine. Not wanting to disappoint my 5 year old, we re-used the battery pack from his wigglebot instead.

To make this project a little more advanced than the last one however, this time we added a switch into the circuit, since removing the battery from within the Slurpie lid would have been basically impossible. To add the switch, my son got to use wire cutters and wire strippers to make a wire to connect the switch to the motor. When we were finished, my kids ended up liking this project just as much, if not more than their wigglebot. It’s movement is a little quicker and more unpredictable, which was exciting.

Check out this YouTube video to see the wobblebot in action.

Since we didn’t get to use our solar panel this time, for our next project, we will likely connect a few solar panels together until we have enough current to power our inexpensive motor. If you’d like to be notified when that tutorial is available, please consider subscribing to our newsletter.

Recommended Age Range: Kindergarten, Elementary, Middle School (younger kids will need adult supervision and assistance since this project uses hot glue)
Time Required: ~30 minutes
Difficulty: Easy
Cost: Less than $10 in used supplies (or much cheaper if you buy supplies in bulk. Buying individually, the motor was $3.50, the battery holder was $1.50, and the switch was $2.50 at Radio Shack (our local electronics store). We actually reused the motor and battery pack from our Wigglebot.)

Materials:

• Blank or unwanted CD or dvd
• Dome-shaped lid from Slurpie or similar drink
• 2 “AAA” battery holder (affiliate link)
• 2 “AAA” batteries
• 1.5-3 V DC Motor (affiliate link)
• SPST (single pole single throw) switch (affiliate link, be sure it’s labeled push-on/push-off, not momentary)
• Short piece of wire (I used 22 gauge, but it’s not really important)
• Pencil with eraser
• 2 Googly eyes (optional)

Supplies & Tools:

• Wire cutters
• Wire strippers
• Needle nose pliers
• Hot glue gun
• Tape (I used electrical, but any kind will work)
• X-acto knife or other cutting tool
• index card or other safe surface for using X-acto knife
• Scissors for cutting tape if needed

Instructions:

1. 1. Cut a short piece of wire (only a couple inches long is fine).

1. 1. Next, adjust the screw and nut on your wire strippers so that the hole is about the size of the metal core within your wire.

1. 1. Use the wire strippers to pull the outer layer off the wire.

It should look about like this.

1. 1. Use the needle nose pliers to bend the ends of short wire to make it easier to attach the wire to the motor and switch.

1. 1. Use the needle nose pliers to bend one end of the wire around one of the motor’s 2 lead and the other end of the wire around one of the switches leads.

1. 1. Next use the same technique to connect one of the wires coming from the battery pack to the motor’s free lead and the other wire coming from the battery pack to the switches free lead. You should end up with your 3 components (motor, switch, battery pack) in a big circle. It doesn’t matter which order or orientation the pieces are in.
   2. Next cut the eraser off of the pencil.

1. 1. Push the eraser into the motor.

1. 1. Hot glue the motor onto the cd with the eraser sticking through the hole. It doesn’t matter which side of the CD faces up.

1. 1. Next, tape the battery pack to the motor and CD

1. 1. Tape the dome lid over the motor and battery pack with the switch sticking through the hole in the top. (Note: At this point, if you’re paying attention, you’ll realize that our switch has magically changed from black to red. That’s because in my carelessness, I accidentally bought a “momentary” switch instead of a push-on/push-off switch, so the wigglebot only worked when we held down the button. We had to make another trip to the electronics store to remedy the situation.)

1. 1. Glue on some googly eyes.

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The idea for this bot came from the book Robotics: Discover the Science and Technology of the Future. The specific project that motivated this activity was the Art-Making Vibrobot on pages 24 to 26, though I modified the supplies considerably and the technique slightly. Basically, this little “robot” is just a cup with marker legs that vibrates and spins due to the motor being off balance. As it jiggles around on a piece of paper it makes interesting designs. While I hope to make more exciting and complicated projects with my kids as they get older, this was a nice unthreatening activity to start with which showed my child how to hook up a simple DC motor to a battery. He’s already familiar with some of these electrical concepts through our Snap Circuits set (link to my review), but this was a fun, hands-on supplement to the more structured activities in that set.

Check out this video if you would like to see a demonstration of how one of our wigglebots moved, though they each have their own unique personality depending on the length and position of the legs.

Recommended Age Range: Kindergarten, Elementary, Middle School (younger kids will need adult supervision and assistance since this project uses hot glue)
Time Required: ~30 minutes
Difficulty: Easy
Cost: Less than $8 in used supplies (The motor was $3.50 and the battery holder was $1.50 at Radio Shack (our local electronics store). Everything else we already had on hand.)

Materials:

• Disposable cup
• Electrical tape
• 3 Markers
• 2 “AAA” battery holder (affiliate link)
• 2 “AAA” batteries
• 1.5-3 V DC Motor (affiliate link)
• Clothespin
• Popsicle stick
• Googly eyes (optional, you could always just draw them on)

Supplies & Tools:

• Scissors
• Permanent marker (to draw face, not shown)
• Glue (optional, for attaching googly eyes. Note that the picture shows Elmer’s Glue, but we ended up finding the hot glue gun worked better.)

Instructions:

1. First, tape the markers into the cup as legs.

2. Next, attach the battery pack to the DC motor by wrapping the wire around the leads on the motor. (When my kids are older, I’ll teach them how to solder, but for now, this is sufficient.)

3. Now that the battery pack is attached to the motor, tape the battery pack onto the top of the disposable cup slightly off-center. I cut the strips of electrical tape in half.

4. Next, tape the DC motor onto the cup.

5. At this point you could turn on the motor by placing the batteries into the holder, to see that with the motor not off balance, nothing exciting happens. Next, add on the clothespin to the motor and it should start to wiggle a little bit.

6. To make the wigglebot wiggle more, you need the motor to be more off-balance. I accomplished this by taping a popsicle stick to the clothespin. However, then my clothespin would frequently fall off of the motor due to the strong vibrations, so I folded the end of a long narrow piece of electrical tape over the motor and then wrapped the tape around the motor so that the sticky side was facing out.

7. Attach the clothespin and weight to the motor.

8. Make a face on your wigglebot, plug in the batteries, place it on a piece of paper and watch it wiggle and spin!

Note that unlike a prepackaged robotics kit which provides very specific instructions, this can be viewed as an open-ended activity. While the “tape fix” to get the clothespin to stick to the motor worked, one could definitely try to think of improvements to be able to cantilever more weight off the axle in order to make the wigglebot vibrate even more. The robotics book mentioned above recommends sticking a piece of cork into the shaft. There are also other adjustments that could be made and you should definitely encourage your child to ask questions and try to find solutions. What would happen if the legs were not all the same length? What if we attached the motor at an angle or sideways? What if we taped on more legs? I don’t know. What if?

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