DIY Science Experiments You Can Do at Home

How to Get an Egg Into a Bottle Without Touching It

Two days in vinegar take the shell away, a warm bottle does the rest. The egg goes through a mouth narrower than itself, pushed by ten tonnes of air per square metre.

How to Make an Underwater Volcano: Convection in a Jar

Hot red water in a salt shaker, lowered into a jar of cold water. It erupts, curls into a mushroom, and lies on the surface like oil, because water one and a half percent lighter has nowhere to go but up.

How to Make a Ping-Pong Ball Float With a Hair Dryer

Point a hair dryer at the ceiling and a ping-pong ball sits in mid-air, wobbling but never falling out. Most explanations of why are wrong, and the real one is better.

How to Push a Skewer Through a Balloon Without Popping It

A wooden skewer goes in at the top of a balloon and out beside the knot, and the balloon just sits there. The trick is knowing where the rubber is least stretched, and why stretch decides everything.

How to Make a Density Tower: Stacking Liquids in a Glass

Honey, washing-up liquid, water, oil and rubbing alcohol, poured one by one into a glass, settle into five sharp layers. Which goes where is decided by one number, and one of them only stays put thanks to the oil.

How to Blow Up a Balloon With Hot Water: Charles’s Law

Put a balloon on an empty bottle, stand the bottle in hot water, and the balloon lifts itself up. The air didn’t get any more of itself. It just needs more room, and from that one fact you can find absolute zero.

How to Make a Tornado in a Bottle: Vortex Science

Swirl an upside-down bottle of water and a funnel of air drills down through the middle. It spins fastest at the centre for the same reason a skater spins faster with arms pulled in, and it has nothing to do with which hemisphere you live in.

How to Make Oobleck: The Liquid That Turns Solid

Cornflour and water, stirred together in a bowl. Stir slowly and it pours like cream; punch it and it cracks like a brick. The grains inside are doing something physicists only pinned down in the last fifteen years.

How to Clean a Penny: Cola, Vinegar and Salt Compared

Leave a dull penny in cola overnight and it comes out shining. Drop it in vinegar with a pinch of salt and it shines in seconds. The difference is one ingredient, and the same chemistry turned the Statue of Liberty green.

How to Do the Egg Drop Inertia Trick: Newton’s First Law

Knock a tray out from under an egg and the egg drops straight down into a glass of water. The trick is speed, not strength, and the egg’s weight turns out not to matter at all.

Why 100 ml + 100 ml Makes Less Than 200 ml

Pour 100 ml of alcohol into 100 ml of water and you get about 192 ml. Nothing leaks, nothing evaporates, and the scale says not a gram is missing. The molecules have simply moved in closer together.

How to Measure the Speed of Light With Chocolate

Take the turntable out of a microwave, heat a bar of chocolate for twenty seconds, and measure the gap between the melted spots. Multiply by the number on the back of the oven and you get the speed of light, give or take a few percent.

How to Make a Barometer With a Jar and a Balloon

Stretch a balloon over a jar, glue on a straw, and the straw tips up and down as the air presses harder or softer. It is a real barometer, with one catch every homemade one shares: it is also a surprisingly good thermometer.

The Pepper and Soap Experiment: Surface Tension Explained

Sprinkle pepper on water, touch the middle with a soapy finger, and the pepper flees to the edge in a split second. It isn’t scared of the soap. The water’s skin is pulling it away.

How to Float a Paper Clip on Water: Surface Tension

Steel is nearly eight times denser than water, and a paper clip still lies on top of it if you put it down gently. The surface bends into a dimple and holds it, like a trampoline, until a drop of soap breaks the spell.

The Dancing Raisins Experiment: How Bubbles Lift a Raisin

Drop raisins into fizzy water and they sink, rise, turn over at the top and sink again, for an hour. Each one is a tiny submarine that fills its own ballast tanks with bubbles and empties them at the surface.

How to Make a Lava Lamp With Oil, Water and a Fizzy Tablet

Oil, coloured water and a fizzy tablet in a bottle: blobs of colour rise, hang at the top and fall back for as long as the fizz lasts. Oil and water refuse to mix, and bubbles do the lifting.

The Ivory Soap Microwave Experiment: Why the Bar Puffs Up

Put a bar of Ivory soap in the microwave and it swells into a cloud several times its size. Hot air alone can’t do that. The water hidden in the soap, turning to steam, can.

The Coloured Carnations Experiment: How Flowers Drink Water

Stand white carnations in coloured water and by the next day their petals have changed colour. The dye has climbed the stem through tubes thinner than a hair, pulled up by the flower itself.

How to Make Invisible Ink With Lemon Juice, and Reveal It

Write with lemon juice, let it dry, and the page looks blank. Warm it and the message darkens into view, because the juice scorches long before the paper does. Spies used the same idea for centuries.

How to Build a Geodesic Dome From Newspaper

Sixty-five rolled-up newspapers, two lengths, a lot of tape: a dome two metres across that you can sit inside. Triangles can’t change shape, and that one fact holds the whole thing up.

How to Build a Marble Run From Cardboard Tubes

Split tubes, a wall and some tape: a zigzag run that keeps a marble busy for half a minute on a one-metre drop it could fall in less than half a second. Height is the fuel; the trick is spending it slowly.

How to Build a Spaghetti Bridge (and Why Pasta Buckles)

One strand of dry spaghetti can hang five kilograms from its end, then buckles under less than two hundred grams pushed along it. A good bridge pulls where pasta is strong and keeps the pushes short.

How to Push a Straw Through a Raw Potato

Stab a potato with a plastic straw and the straw crumples. Put your thumb over the top first and it goes straight through. The air trapped inside can’t get out, so the straw can’t cave in.

How to Make a Simple Electric Motor (Homopolar Motor)

A battery, a magnet and a bent piece of copper wire: three parts, no coils, and the wire spins on its own. It is the same push that drives every electric motor, found by Faraday in a single afternoon in 1821.

How to Build a Cotton Reel Tank (Thread Spool Tank)

An empty cotton reel, a rubber band, a pencil and a slice of candle. Wind it up and it crawls across the floor and over books, slowly giving back every turn you put in.

How to Make a Cardboard Boat That Floats (and Carries Coins)

One sheet from an old box, folded into a tray and sealed with tape and wax. Then the test: how many coins can it carry before the water comes over the side?

How to Make a Cardboard Chair That Holds Your Weight

Nothing but cardboard: no glue, no tape, no screws. Just slots, folds and the flutes the right way up, and a chair that holds a grown-up.

How to Build a Boat Powered by a Chemical Reaction

A bottle, a straw, a spoonful of baking soda and a splash of vinegar. The fizz has only one way out, and when it rushes out the back the boat shoots off the other way, like a tiny rocket.

How to Make a Cartesian Diver With a Straw and a Bottle

A scrap of straw, a pinch of plasticine and a bottle of water. Squeeze the bottle and the diver sinks; let go and it floats back up, without ever being touched.

Balloon Car Race: How to Make a Balloon-Powered Car

Half a cup, four bottle tops, two skewers and one balloon. Blow it up, let it go, and a jet of your own breath sends the car racing across the floor.

How to Design and Build a Paper Helicopter That Spins

A strip of paper, three snips and a paper clip. Drop it from up high and it doesn’t fall: it whirls, spinning its way gently to the floor like a sycamore seed.

How to Make a Water Clock That Times Exactly One Minute

Two plastic cups, a pinhole and three-quarters of a cup of water. Tune the hole until it runs dry in exactly sixty seconds, and you have built the oldest kind of clock there is.

How to Build a Compass With a Needle, a Magnet and Water

A sewing needle, a magnet and a bowl of water. Fifty strokes turn the needle into a magnet, and floated on the water, it swings round to feel the invisible field of the whole Earth.

Jelly and Oil: A Friction Experiment With Chopsticks

Move cubes of jelly from one plate to another with chopsticks. Easy. Now coat them in oil and try again, and find out how much of everything you hold depends on friction.

How to Make a Potato Battery That Powers a Clock

Two potatoes, two nails and two scraps of copper. Wire them in a row and a clock with no battery starts ticking, powered by metal slowly dissolving inside a vegetable.

A Tough Nut to Crack: How to Open a Brazil Nut Whole

A bag of Brazil nuts and a nutcracker. Squeeze one flat and it shatters; squeeze one on its ridge and the shell falls open around a perfect kernel. The difference is where you press.

How to Make a Homemade Paper Water Bomb (Origami)

One square of paper, no glue, no scissors. A dozen folds and a puff of breath turn it into a cube that holds a cupful of water, for just long enough to drop it.

How to Make a Periscope With Two Mirrors and a Box

Two juice cartons and two small mirrors. Set the mirrors at exactly 45° and you can see over walls, round corners and above a crowd, without ever showing your head.

Attractive Nails: How to Make an Electromagnet

A nail, a length of wire and a battery. Wind the wire round the nail and touch it to the battery, and the nail becomes a magnet that picks up paper clips, until you let go.

Lenz’s Law: Why a Magnet Falls Slowly Through Copper

Drop a magnet down a plastic tube and it is gone in a blink. Drop it down a copper pipe, which isn’t magnetic at all, and it drifts down as if through honey.

How to Make an Electromagnetic Train With a Battery

A coil of bare copper wire, a battery and six magnets. Push the battery into the coil and it shoots off on its own, carrying its own electromagnet with it.

Metal Etching: How to Etch Steel With Salt Water and a Battery

A scrap of steel, a bowl of salt water and a 9 V battery. Draw on the metal, switch on, and twenty minutes later your drawing stands proud of a surface the current has eaten away.

How to Make a Fire Extinguisher With Baking Soda and Vinegar

A jar, some baking soda and a splash of vinegar. Tip the jar over a candle as if pouring water, and the flame goes out, smothered by a gas you can’t see.

How to Make a Balance Bird That Perches on Its Beak

A bird cut from card, two coins and a fingertip. It balances on the very tip of its beak, rocks when you nudge it, and settles back, as if it had decided to stay.

How to Make a Paper Microscope With a Glass Bead Lens

A strip of card, a glass bead the size of a grain of sand and a slip of sticky tape. Hold it to your eye and an onion skin becomes a wall of cells.

How to Build a Level-One Menger Sponge From Business Cards

A hundred and twenty business cards, folded into twenty cubes and locked together without glue. The first step of a shape with no volume and an infinite surface.

How to Construct the Spiral of Theodorus With a Ruler

A ruler, a square corner and a pencil. Build one right triangle on another and draw every square root from √2 to √17, curled into a snail shell.

How to Make a Hyperbolic Slot: A Straight Rod Through a Curve

A pencil, a skewer and a sheet of foam board. Spin a perfectly straight stick and it glides through a perfectly curved slot, thanks to the shape of a cooling tower.

How to Make Square Wheels That Roll Smoothly on a Bumpy Road

Two cardboard squares, a skewer and a necklace. Trace a hanging chain, turn it upside down for a road, and square wheels roll as smoothly as round ones.

How to Show the Area of a Circle Is πr² With Paper Slices

A paper circle, three folds and a pair of scissors. Cut it into slices, lay them top to tail, and the circle becomes a rectangle that shows why its area is πr².

How to Make a Galton Board That Draws a Bell Curve

A board, forty pins and a handful of beads. Every bead zigzags at random, yet together they pile into the same graceful hump every time: the bell curve.

How to Make a Pendulum Wave Toy From Nuts and String

Twelve nuts on twelve strings, each a little shorter than the last. Let them go together and they weave waves and snakes, then swing back into a perfect line.

How to Make the Missing Square Puzzle and Find the Trick

Four pieces of card make a triangle. Swap two of them round and the same pieces make the same triangle, with a square missing. Where did it go?

How to Make Moiré Patterns With Two Grids and a Turntable

Two squares of black mesh and a turntable. Spin one grid under the other and giant shimmering squares bloom and swirl, a pattern that exists in neither grid.

How to Make a Harmonograph That Draws With a Pendulum

A broom handle, a board on a Y of string and a felt-tip pen. Set it swinging and the pen draws figures of eight and woven shells, the shapes of musical harmony.

How to Make a Wave Machine From Skewers, Tape and Sweets

Two stools, a strip of duct tape, fifty skewers and a bag of jelly sweets. Tap one end and a wave you can watch ripples down the line and bounces back.

How to Make a Box Kite That Flies Without a Tail

Eight dowels, eight bits of tube and two bands of sail. Snap them into two open boxes and you have the kite that lifted a man off a beach in 1894.

How to Make a Paper Sphere From Six Woven Strips

Six strips of card, ten pencil marks on each and some patience. Weave them together and they close into a springy ball with 12 pentagon holes and 20 triangles.

How to Draw a 3D Hand Optical Illusion With Curved Lines

Trace your hand, then draw nothing but lines across the page, each arching up as it crosses the outline. Thirty lines later, your hand rises off the paper.

How to Build a Giant Cardboard Windball From 30 Squares

Thirty squares cut from old boxes, joined only at their corners. Clip them round rings of three and five and they curl into a ball a metre across.

How to Make a Conveyor Belt Cinema From a Box and Two Tubes

A shoebox, two cardboard tubes and a strip of paper. Turn the crank and the scenery rolls past a cut-out car, which seems to drive though it never moves.

How to Make a Rocket Toy From the Recycling Bin That Flies

A plastic bottle, a scrap of paper and a corner of a cereal box. Roll a rocket, give it fins and a clay nose, then squeeze and watch it streak across the garden.

How to Make 3D Folding Paper Letters From Flat Nets

A sheet of card, a ruler and some careful folding. Two letter-shaped faces and one long strip make a bold 3D letter; make a few and spell out a name.

How to Make Geometric Paper Wall Art From Folded Triangles

Square sheets of coloured paper, one classic origami fold and a board. Fold two dozen identical triangles, turn them this way and that, and a pattern takes over the wall.

How to Make a Moon-Themed Clock With a Moon Phase Window

A full moon for a clock face, a battery movement and a hand-turned phase window. It keeps the time to the second and, with a nudge every few days, keeps pace with the Moon.

How to Make Melted Crayon Art With a Hair Dryer

A row of crayons glued to a canvas and a hair dryer on its hottest setting. The wax melts, gravity takes over, and streams of colour run down until they set.

How to Make a Color-Coded After-School Routine Clock

A plain white wall clock and five pots of paint. Paint each part of the afternoon as a slice of the face and the hour hand shows what comes next.

How to Make a Paper Rocket Garland With Slotted 3D Rockets

Two flat paper rockets and one slit each. Slot them together, string a fleet along a cord, and the cord draws a curve that took mathematicians fifty years to solve.

How to Make a Rocket Man: A Cardboard Box Rocket for Kids

A big packing box, yogurt pots and cotton reels become a rocket a child can climb inside, and a way into the equation that makes real rockets almost all fuel.

How to Decorate Power Cords With Washi Tape and Leather Ties

A grey extension lead, a few rolls of washi tape and some leather scraps. Wrap it in bright bands, make snap ties for the spare length, and learn why coiled cords run hot.

How to Make Forts at Home With Blankets, Chairs and Pegs

Two chairs, a broom and the biggest blanket in the house. Build a fort that stays up, find the slope that gives the most room, and learn why triangles never wobble.

How to Make a LEGO Macintosh Classic With an E-Paper Display

A Raspberry Pi the size of a stick of gum, a screen made of electric ink and a case of grey bricks. Build a working mini Macintosh and paint pictures in black and white.

How to Make a Wooden Domino Row Building Machine

A little cart with a cam on its wheel lays a row of perfectly spaced dominoes as it rolls. Then knock the first one and learn why a domino can topple one half as big again.

How to Make a Hexaflexagon From a Strip of Paper

A strip of ten paper triangles folds into a hexagon with three faces instead of two. Pinch, push and open, and a face you never coloured blooms from inside.

How to Make a Pinhole Camera From a Shoebox

A shoebox, a square of foil and a needle. Prick one tiny hole and the world outside appears on a paper screen, in colour, moving and upside down.

How to Make a Kaleidoscope From a Kitchen-Roll Tube

Three strips of mirror in a kitchen-roll tube and a pinch of beads. Turn it to the light and a jumble of sequins becomes a perfect, ever-changing pattern.

How to Make a Sundial From a Paper Plate

A paper plate, a pencil and the turning Earth. Tilt the plate to your latitude, point the pencil at the pole star, and the shadow turns 15° every hour.

How to Make Reuleaux Triangle Rollers That Roll Like Circles

Three curved triangles cut from card, and a book that glides across them as smoothly as on round rollers. Not every shape that rolls is a circle.

How to Make Straw Pan Pipes That Play a Real Scale

Eight straws, a ruler and a lump of clay. Cut them to length, seal the bottoms and blow: a whole octave, tuned by nothing but the speed of sound.

How to Make a Tangram From a Square of Card

One square of card, five straight lines, seven pieces. Rearrange them into cats, boats and swans, and every picture has exactly the area of the square.

How to Make a Spectroscope From a CD and a Cereal Box

An old CD and a cereal box make a real scientific instrument. Point it at the sky, a lamp or a street light and see the hidden colours each one is made of.

How to Make a Balloon Hovercraft From an Old CD

An old CD, a bottle cap and a balloon. Open the cap and the disc lifts a hair’s breadth off the table, then glides away at the faintest touch.

How to Make a String Telephone From Paper Cups

Two cups, a long string and a friend at the far end of the garden. Whisper into one cup and your voice arrives at the other, carried by a shaking thread.

How to Make a Pizza Box Solar Oven That Really Cooks

An empty pizza box, some foil, black paper and cling film. Point it at the Sun and in half an hour the chocolate melts and the marshmallows go gooey.

How to Make Ice Cream in a Bag With Ice and Salt

Milk, sugar and vanilla in one bag; ice and salt in another. Ten minutes of shaking makes real ice cream, colder than a freezer can get.

How to Make an Archimedes Screw That Lifts Water

A plastic bottle wrapped in a spiral of tubing. Dip one end in water, turn it, and water climbs up and pours out at the top, though not a drop flows uphill.

How to Make a Cup Anemometer to Measure Wind Speed

Five paper cups, two straws and a pencil. Set it spinning in the breeze, count the turns for thirty seconds and work out how fast the wind is blowing.

How to Make a Cloud in a Jar With Hot Water and Ice

Hot water, an icy lid and one puff of hairspray. Within seconds a little white cloud churns inside the jar, made the same way clouds form in the sky.

How to Make a Popsicle Stick Catapult That Hits the Target

Nine lolly sticks, a few rubber bands and a plastic spoon. Press, let go, and a marshmallow sails across the room on a perfect parabola, straight into a cup.

How to Make Rock Candy Crystals on a Stick

Sugar, water and a week of patience. Dissolve far more sugar than cold water can hold, hang a seeded stick in the syrup, and watch crystals grow day by day.

How to Make Walking Water: A Rainbow That Climbs Paper

Five glasses, some paper towels and three colours. Over a few hours the water climbs the paper, walks into the empty glasses and mixes into a rainbow.

How to Make an Abacus: A Soroban From a Shoebox Lid

A shoebox lid, five skewers and 25 beads become a Japanese soroban that counts to 99,999 and makes place value and carrying visible.

How to Make a Zoetrope: Spin Drawings Into Motion

A ring of black card with twelve slits and twelve drawings of a ball. Spin it, look through the slits, and the ball bounces.

How to Make a Möbius Strip and Cut It in Two Ways

A paper strip, a half-twist and some tape make a loop with one side and one edge, which refuses to fall apart when you cut it in half.

How to Make a Slide Rule That Multiplies With Logs

Two strips of card marked with logarithmic scales. Slide one along the other and they multiply and divide, the way engineers calculated for 350 years.

How to Make a Clinometer and Measure a Tree’s Height

A protractor, a straw and a weighted thread. Sight the top of a tree, read one angle, pace one distance, and trigonometry gives you its height.

How to Make a Hydraulic Arm With Syringes and Water

A cardboard arm, four syringes and a tube of coloured water. Push one plunger and the arm lifts: a tiny digger driven by water pressure.

How to Make a Parachute for a Toy From a Plastic Bag

A square of plastic bag, four strings and a toy. Drop it and it floats down, slowed by the air it pushes aside, at a steady terminal speed.

Buffon’s Needle: How to Find π by Dropping Toothpicks

Drop toothpicks on lined paper and count how many land across a line. Out of pure chance comes π, the number of circles, from a game with no circles in it.