1x Arduino Uno board.
A programmable microcontroller. It controls electrical circuits according to the programs you load onto it.
1x half-size breadboard.
An easy way to make circuits. Check online or in a book to learn how it’s wired.
1x USB-A to USB-B cable.
The flat end plugs into your computer; the squarish end plugs into the Arduino. It provides both power and a data connection.
Wires.
For making connections on the breadboard and Arduino pins.
5x green LEDs and 5x red LEDs.
Light! Always use a resistor, or you will burn it out. The long leg must go to the power connection.
5x 150-ohm resistors and 5x 180-ohm resistors.
Slow down current, e.g. to avoid overloading components. The printed bands are color-coded to indicate resistor strength. Brown-gray-brown is 180Ω, brown-green-brown is 150Ω.
1x potentiometer.
Varies resistance based on how you turn the knob, like a dimmer switch. (Note: does not work as a simple dimmer for the LEDs.)
1x photoresistor.
Changes resistance according to how much light strikes it. Use it as a light sensor.
4x push buttons.
Spring-loaded switches.
1x piezo buzzer.
Vibrates to produce sound. Rate of vibration changes tone. Can also be used as a vibration sensor.
1x transistor.
A switch that closes a circuit when it receives a signal on its base (middle) pin. Can also be used to amplify a signal.