1029 science project ideas, from class 1 to college.

What it shows

A light dependent resistor (LDR) has a high resistance in the dark and a low resistance in light. A transistor uses that change to switch the LED on when it gets dark.

You will need

• An LDR
• A BC547 transistor
• Resistors, including a 10 kΩ variable resistor
• LEDs
• A 9 V battery and clip
• A breadboard and jumper wires

Safety: Battery power only.

What it shows

Tap water conducts a little electricity because of the salts dissolved in it. As the water rises it touches wires at different heights, and transistors light an LED or sound a buzzer for each level.

You will need

• Insulated wires with bare ends
• BC547 transistors
• LEDs, resistors and a buzzer
• A 9 V battery
• A container and a breadboard

Safety: Battery power only: never use the mains near water.

What it shows

An ultrasonic sensor sends out a pulse of sound and times its echo to measure distance. When a hand comes close, the Arduino tells a servo motor to lift the lid.

You will need

• An Arduino Uno and USB cable
• An HC-SR04 ultrasonic sensor
• An SG90 servo motor
• A small dustbin
• Jumper wires and a battery pack

What it shows

The robot measures the distance ahead with an ultrasonic sensor. When something is too close, the program stops, turns and looks for a clear path, driving the motors through a motor driver.

You will need

• An Arduino Uno
• An HC-SR04 ultrasonic sensor, with a servo to turn it (optional)
• An L298N motor driver
• A robot chassis with two geared motors and wheels
• A battery pack and a switch

Safety: Use a proper battery holder and never short-circuit lithium cells.

What it shows

IR sensors shine infrared light at the floor: white reflects it and black absorbs it. The controller reads which sensor sees the line and steers the motors to stay on it.

You will need

• An Arduino or a comparator board
• Two or more IR sensor modules
• A motor driver and two geared motors
• A chassis, wheels and a castor
• Black tape on a white sheet for the track

What it shows

A soil moisture sensor gives a reading that changes with the water in the soil. When the soil is dry, the Arduino switches on a small pump until it is moist again.

You will need

• An Arduino Uno
• A soil moisture sensor
• A small low-voltage pump with tubing
• A relay or transistor driver module
• A pot plant and a water container

Safety: Keep the electronics away from water, and use only a low-voltage pump.

What it shows

Two LDRs compare the light on either side of the panel. The microcontroller turns a servo towards the brighter side, so the panel keeps facing the Sun and collects more energy through the day.

You will need

• An Arduino or similar board
• Two or four LDRs with resistors
• Servo motors
• A small solar panel
• A frame and a power supply

What it shows

A Wi-Fi board receives commands from a phone app or web page and switches relays, so lights and fans can be controlled from the phone and on a schedule.

You will need

• A NodeMCU (ESP8266) or ESP32
• A relay module
• Low-voltage DC lamps or a demonstration board
• A power supply
• A phone app or web dashboard

Safety: Build the prototype with low-voltage loads. Any mains wiring must be done by a qualified electrician.

What it shows

IR sensors detect the train before and after the crossing. The controller closes the gate with a servo and sounds a buzzer as a train approaches, and opens it again once the train has passed.

You will need

• An Arduino
• Two IR sensor modules
• A servo motor
• A buzzer and LEDs
• A model track and gate

What it shows

Flame sensors detect the infrared light from a flame. The robot steers towards the strongest reading and switches on a small pump to spray water at it.

You will need

• An Arduino
• Flame sensor modules
• A motor driver, chassis, motors and wheels
• A small pump, tubing and a water tank
• A battery pack

Safety: Test only with a small candle, under adult supervision, with water ready.

What it shows

An accelerometer detects a sudden impact or tilt. The controller reads the location from a GPS module and sends it by SMS through a GSM module to saved numbers.

You will need

• An Arduino or ESP32
• An accelerometer such as the ADXL335 or MPU6050
• A GPS module
• A GSM module and a SIM card
• A power supply suited to the GSM module

What it shows

Each card carries an RFID tag with a unique ID. The reader picks up the ID by radio when the card is held near it, and the controller logs the name and time.

You will need

• An Arduino
• An RC522 RFID reader and cards
• An LCD display, or a computer for the log
• A real-time clock module
• A buzzer and LEDs

What it shows

The resistance of an MQ-series gas sensor changes when LPG or smoke is in the air. The controller reads it and sounds a buzzer above a set level.

You will need

• An MQ-2 or MQ-6 gas sensor module
• An Arduino or a comparator circuit
• A buzzer and an LED
• A power supply

Safety: Test with a short puff of gas from an unlit lighter, with an adult, away from flames. A school model does not replace a certified home gas detector.

What it shows

A phone app sends commands over Bluetooth to an HC-05 module. The Arduino reads them and drives the motors forwards, backwards, left and right through a motor driver.

You will need

• An Arduino Uno
• An HC-05 Bluetooth module
• An L298N motor driver
• A chassis, motors and wheels
• A battery pack and a phone app

What it shows

A switch is just a gap in a circuit that can be closed. Two foil sheets held apart by a foam ring touch when pressed, completing the circuit so current flows through the LED.

You will need

• Two pieces of stiff card, about 10 cm square
• Kitchen aluminium foil
• A foam sheet or thick cardboard ring with a hole cut in the middle
• One red LED and a 150 Ω resistor
• A 2 x AA battery holder with two AA cells (3 V)
• Two 30 cm lengths of insulated wire
• Glue, tape and scissors

Safety: Scissors only with an adult nearby. Keep the foil sheets from touching the battery terminals directly, which would warm the cells.

Take it further: Hide the pad under a doormat and swap the LED for a 3 V buzzer to make a visitor alarm.

What it shows

A light dependent resistor has a low resistance in bright light and a very high resistance in the dark. In a voltage divider with a fixed resistor, this change swings the base voltage of a transistor, which switches a buzzer on when it gets dark.

You will need

• One LDR (5 mm or 10 mm)
• One BC547 transistor
• A 10 kΩ resistor and a 1 kΩ resistor
• An active buzzer rated 3 to 12 V
• A 9 V battery with a snap connector
• A breadboard and jumper wires

Safety: Battery power only. Do not short the 9 V battery terminals; it gets hot.

Take it further: Replace the 10 kΩ resistor with a 100 kΩ potentiometer so you can set the darkness level with a knob.

What it shows

When an LDR is placed in series with an LED, more light lowers the LDR resistance, more current flows and the LED glows brighter. The LED becomes a simple meter for how bright the room is.

You will need

• One LDR
• One red LED and a 330 Ω resistor
• A 9 V battery with a snap connector
• A breadboard and jumper wires
• A torch and a sheet of paper for testing

Safety: Battery power only. Do not point a bright torch into anyone’s eyes.

Take it further: Put a multimeter on the current setting in the loop and make a table of milliamperes against each place you tested.

What it shows

Tap water conducts a small current because of dissolved salts. Two BC547 transistors joined as a Darlington pair multiply that tiny current enough to drive a buzzer, so the alarm sounds the moment water bridges the probe wires.

You will need

• Two BC547 transistors
• A 100 kΩ resistor and a 10 kΩ resistor
• An active buzzer rated 3 to 12 V
• A 9 V battery with a snap connector
• Two 50 cm insulated wires with 2 cm bare ends as probes
• A breadboard, jumper wires and a bucket of tap water

Safety: Battery power only; never use mains electricity near water. Dry your hands before touching the breadboard.

Take it further: Add two more probe pairs with their own LEDs at half and three quarters to make a full level indicator.

What it shows

Raindrops bridge the gap between two sets of foil strips that are close but not touching. The water lets a tiny current flow, which a Darlington pair of BC547 transistors amplifies to sound a buzzer, warning you to bring the washing in.

You will need

• A plastic sheet or laminated card about 10 x 15 cm
• Aluminium foil cut into 5 mm strips
• Two BC547 transistors
• A 100 kΩ resistor and a 10 kΩ resistor
• An active buzzer rated 3 to 12 V
• A 9 V battery with a snap connector
• A breadboard, jumper wires, glue and a dropper of water

Safety: Battery power only. Keep the breadboard and battery indoors and dry; only the sensor card goes outside.

Take it further: Replace the buzzer with a 5 V relay module and let the relay switch on a bigger battery-powered lamp indoors.

What it shows

A telegraph key is a spring switch that closes a circuit for short or long moments. Pressing the paper clip onto a drawing pin completes the loop, and the pattern of short and long beeps carries letters in Morse code.

You will need

• A large paper clip and two drawing pins
• A small wooden block or thick cardboard base
• An active buzzer rated 3 to 12 V
• A 2 x AA battery holder with cells (3 V)
• Three short insulated wires
• A printed Morse code chart

Safety: Drawing pins are sharp; an adult should push them into the block. Keep small parts away from younger children.

Take it further: Add an LED with a 150 Ω resistor in parallel with the buzzer so the message can be seen as well as heard.

What it shows

Two keys and two indicator LEDs on one long wire pair let either station send to the other. It shows that a signal is really a current switched on and off, and that one shared return wire is enough for a two-way line.

You will need

• Two paper clip keys on wooden blocks (see the single key project)
• Two red LEDs and two 150 Ω resistors
• A 2 x AA battery holder with cells (3 V)
• About 10 m of twin insulated wire (bell wire or old speaker wire)
• Tape and a Morse chart for each station

Safety: Run the long wire along a wall, not across a doorway where someone could trip.

Take it further: Replace each LED with an active buzzer in parallel with the LED and compare how far the sound carries.

What it shows

Each question fastener is secretly wired to its correct answer fastener behind the board. Touching the two probes to a matching pair completes the circuit and lights the LED, so the board tests both knowledge and the idea of a closed loop.

You will need

• A sheet of stiff cardboard about A3 size
• Twelve brass paper fasteners (split pins)
• Aluminium foil strips or thin insulated wire for the hidden links
• One red LED and a 150 Ω resistor
• A 2 x AA battery holder with cells (3 V)
• Two 40 cm probe wires with bare tips
• Tape, a marker and a list of six questions with answers

Safety: Split pins have sharp points at the back; an adult should press them through and fold them flat.

Take it further: Add a second LED of another colour and a buzzer so the board can give sound and light for a correct answer.

What it shows

A motor spinning an unbalanced weight shakes the whole brush. The angled bristles push forward on every shake and slip backward on the return, so the vibration turns into movement in one direction.

You will need

• A cheap plastic scrubbing brush or a large toothbrush head
• A 3 V DC toy motor
• A blob of hot glue or a small bead and tape for the off-centre weight
• A 2 x AA battery holder with a switch and cells (3 V)
• Double-sided tape or hot glue
• Two pieces of wire

Safety: An adult must handle the hot glue gun. Keep fingers away from the spinning shaft.

Take it further: Build a second bristlebot and race them, changing the weight and bristle angle to see which design wins.

What it shows

An unbalanced motor on a plastic cup makes it wobble on three marker legs, and the wobble is traced out as a looping drawing. The pattern depends on the weight, the speed and how far apart the legs are.

You will need

• A plastic cup or an empty yogurt tub
• Three sketch pens or markers
• A 3 V DC toy motor with a glue blob or a cork piece fixed off centre on the shaft
• A 2 x AA battery holder with a switch and cells (3 V)
• Rubber bands and tape
• A large sheet of paper

Safety: An adult must use the hot glue gun. Keep marker caps and small parts away from toddlers.

Take it further: Add a second motor spinning the opposite way and see whether the drawings become straighter or more tangled.