Bruce's Workbench
Step-by-step construction plans for 73 of Bruce's homemade demonstration devices, drawn from the handouts he has shared with teachers for decades. Every plan includes materials, tools, photos, the physics and ways to use it. Each one downloads as a free PDF.
Air-Powered String Shooter
A loop of yarn shoots out of a PVC pipe and snakes through the air in a self-supporting arc, driven by nothing but a shop vac's exhaust.
Balloon in a Bottle
Blow up a balloon inside a bottle and it stays inflated with its mouth wide open.
Cartesian Diver Collection
Squeeze a sealed bottle and a little diver sinks on command; let go and it floats back up.
Diving Dan Remote Bottle Diver
Squeeze a bottle on the pool deck and a diver 10 feet down rises to the surface.
Hydraulic Syringe Pairs
Push one plunger and feel the other one push back, multiplied.
Pascal Bottle
Label a water bottle 'Do Not Squeeze!' and wait for someone curious to find out why.
Spool and Card Bernoulli Puzzle
Blow hard through a spool and the card underneath refuses to fall off.
Straw Atomizer and Popcorn Launcher
Blow across one straw and water climbs another and sprays out as a fine mist.
Tantalus Cup
Fill it past the red line and the whole cup drains away through its own bottom.
Venturi Vacuum Pump
Blow air through a plastic T fitting and it sprays water, crushes bottles and cans, and holds Magdeburg hemispheres together, with no moving parts.
Magdeburg Hemispheres Without a Pump
No vacuum pump needed: a long hose of water lowers the pressure inside the sphere so strong students cannot pull it apart.
Tall Clear Demonstration Tanks
A five-foot column of rainbow water in the classroom window starts with a plastic tube and a disk of epoxied plastic.
No-Magnet Motor (Double-Coil Motor)
Students who have built the classic coil-and-magnet motor are always surprised that it still spins when the magnet is swapped for a coil of wire around a bolt.
Tangent Galvanometer
Clip on one wire and a hanging bar magnet swings to face across a ring of copper wire; reverse the battery and it spins all the way around.
Circuit Demonstration Boards
Seven small wooden boards turn abstract circuit diagrams into bulbs that students can light, dim and puzzle over with their own hands.
Glove Light Bulb
Who says a light bulb has to be made of glass? This one glows inside a rubber glove.
Homemade Battery Tester (Simple Galvanometer)
Touch a battery to the post and a straw needle swings up to tell you if it is good, weak or dead, using nothing but a coil of wire and a magnet.
Rheostat Speed-Control Board
Slide a clip along a coil of wire or a split pencil and watch a little motor speed up and slow down, just like a dimmer switch.
Baby Van de Graaff Generator
A soda can, a rubber band and a toy motor add up to a static generator that throws a one-inch spark and launches pie pans off its top.
Activation Energy Track
The ball sits up high, full of potential energy, yet it can't go anywhere until you lift it a little higher.
Fruit Racers
Pick a fruit, add wheels, and race it down a tilted table in a family-night challenge built on potential energy.
Rolling vs. Sliding Batteries
Two identical batteries race down a gentle slope: one rolls, one rides on tiny toy-car wheels. Most people bet on the wrong one.
High Road, Low Road Tracks
Two balls race across side-by-side tracks, and the one that takes the longer road through a dip wins every time.
Open-Works Wall Clock
Take the case off a yard-sale clock and its spring, gears and pendulum become a working lesson on energy.
Plastic-Strip Solar Motor
Put two plastic cups wrapped in stretched trash-bag strips in the sun and they start spinning on their own, with no batteries, solar cells or wires.
Cold Floaters, Hot Sinkers Buoyancy Bottles
The same little bottle floats in cold tap water and sinks to the bottom in hot.
Adjustable Angle Mirrors
Close the angle between two mirrors and one line on a card becomes three, five, seven, even eleven copies.
Water Lens Word Flip
Fill a clear tube with water and one word on the sign turns upside down while the word next to it stays perfectly readable.
Classroom Wall Mirrors
Three mirrors on the wall, three different versions of you: magnified, shrunk, and repeated twenty-one times.
Hand-Held Strobe Light
A flashlight shining through a spinning slotted disk can freeze a dripping faucet, a vibrating string or a bouncing ball in mid-air.
Face vs. Face Profile Vase
Look at it one way and it's a vase; look again and it's two faces nose to nose, and the faces are yours.
Chemical Dice
Roll a positive die and a negative die, and whatever comes up, write the compound's formula and name.
Poke a Polymer
Slide a sharp stick right through a balloon, or a dozen pencils through a bag of water, and nothing pops or leaks.
Rainbow Density Column
Six cups of colored salt water, poured carefully, stack themselves into a rainbow that holds its stripes.
Buoyancy of Sand Vibrating Tub
Switch on the motor and buried ping-pong balls pop up through solid sand while steel balls on top sink out of sight.
Metric Clock
Hang a clock with only ten numbers on it and watch every student in the room start doing math.
Metric Measuring Sticks
Ten wooden sticks, four metric units per stick, and one deliberate mistake for students to catch.
Balancing Nails Challenge
Twelve big nails balanced on one nail head looks impossible. Then Bruce doubles it.
Bar Pendulum vs. Simple Pendulum
A swinging meterstick keeps the same beat whether it hangs from its end or from a point a third of the way down. Why?
Block Stacking Challenges
How few blocks does it take to make the top block hang completely past the edge of the bottom one?
Centrifugal Bottles
Spin two jars of water and everyone expects the floats to fly outward. They move inward instead.
Centripetal Swinging Tray
Swing a full cup of water over your head, then sideways, without spilling a drop.
Falling Weight and Wrap-Around Stopper
Let go of a tiny weight and it whips around a bar so fast it catches a weight fourteen times heavier before it hits the table.
Impulse Blowgun and Egg-in-a-Sheet
Cut the barrel shorter and shorter and watch the marshmallow fall shorter every time.
Projectile Curve Model
Eleven balls hanging from a ceiling bar trace the exact curve of a thrown ball, and you can throw a real one right alongside it.
B-2 Model Hovercraft
A foam meat tray, two cups and a pair of toy motors become a hovercraft that floats on a cushion of air and glides across the floor.
Dynamics Carts and Crashing Blocks
Release two carts pressed together and they shoot apart at the same speed; triple the mass of one and it moves only a third as fast.
Giant Newton's Cradle
Swap the desk toy's tiny steel balls for billiard balls and the whole class can see momentum pass down the line.
Identical Curved Tracks
Release one ball from near the top of a curved track and another from near the bottom, and they hit the end at the same moment.
Ramp Walking Bunny
Set this wooden bunny at the top of a gentle slope and it rocks, swings its back legs forward and hops its way to the bottom with no motor at all.
Spinning Chain and Rope Loops
Flick a spinning loop of chain off a foam wheel and it rolls across the floor like a solid hoop.
Stringless Pendulum Tracks
Three balls roll back and forth on three curved tracks, and you can see the 1, 2 and 3 second pendulums keeping their beat without a single string.
Tape Measure Racer
Pull a tape measure out 12 feet, let go, and the spring that rewinds the tape launches your car another 25 feet past the start.
Giant See-Through Tumbling Toy
A wooden body somersaults end over end down a pair of notched rails, and the clear sides let everyone watch the steel ball inside that makes it happen.
Cardboard Rubber Band Car
A shipping box, a few straws and a rubber band become a car that can roll more than 20 feet, and with giant wheels, more than 100.
Classroom Pulley System (Small-Load Version)
Lift the same bucket of sand with one pulley, then two, three and four, and feel the pull get easier while you measure exactly what it costs you in rope.
Toy Dissection Lab and Display
Take apart a broken toy to find the gears, levers and cams hiding inside, then put it back together as a see-through display.
Homemade Gears
With a compass, a ruler and a little arithmetic you can make working gears from cardboard or wood and see exactly how they trade speed for force.
Lever Larry
Squeeze two wooden handles and a jointed wooden acrobat flips, swings and somersaults over the bar like a high-bar gymnast.
Tabletop Trebuchet
A half-kilogram counterweight swings a long arm and a string sling to fling a rubber ball across the room, just as medieval siege engines did.
Trammel of Archimedes
Crank the handle as fast as you like: the two sliding blocks race toward each other and never collide.
Balloon Fog Horn
Blow into a little plastic bottle and it lets out a deep, buzzing honk like a ship in the fog.
F.A.K.E.D. Resonance Pendulums
Ask the class to move just the orange ball with their minds, and watch it swing while the other three hang nearly still.
Nanosecond of Light and Millisecond of Sound Sticks
Two sticks of almost the same length: one shows a billionth of a second of light, the other a thousandth of a second of sound.
Sneaky Pendulums (Coupled Pendulums)
Tie two sneakers to a string, swing one, and watch the other slowly steal all its motion, then give it back.
Sound Tubes
Put your ear to the end of a long cardboard tube and the room's background noise turns into a soft, steady musical note.
Straw Flutes and Slide Trombones
Snip a drinking straw into a reed and it honks; snip it shorter and the note climbs; slide a second straw inside and it becomes a trombone.
Tin Can Telephone
No batteries, no bills, no signal bars: just two cans, a long string and vibrations.
Toy Motor Speaker
A cheap toy motor already has a coil and magnets inside, so hook it to an amplifier and it will play music through a foam dinner plate.
Chladni Plate Speaker Driver
Sprinkle salt on a plastic sheet, dial up a tone, and watch the grains rush into sharp geometric patterns.
Foam Plate Speaker
Fifty feet of thin copper wire, a cereal-box tube and a strong magnet make a foam dinner plate loud enough to hear from the next room.
Slinky Wilberforce Pendulum
Pull it down and let go: within a few bounces the up-and-down motion turns completely into twisting, then back again.
Standing Wave Gadget
A one-battery motor hanging on a string turns a plain cord into a row of glowing, motionless loops.
No plans match that yet.
Want a ready-made parts kit for one of these? Tell us which build. Looking for the 17 devices in Bruce's NSTA book? About the book.