Use case: A night light that automatically lights a soft LED when someone (kid or pet) enters the room — teaches electronics, basic Python, sensors, and small automation.

What you’ll build (quick)

When PIR motion sensor detects movement, the LED strip (or single LED) turns on for 30 seconds. Optionally a gentle chime plays and a notification can be sent to a phone (advanced).

Parts & tools

• Raspberry Pi Model B (any Model B — Pi 3B/3B+/4B will work)
• microSD card (8GB+) with Raspberry Pi OS installed
• USB power supply for Pi (official 5V 2.5A or suitable)
• PIR motion sensor (HC-SR501)
• LED (single 5mm) or small 5V LED strip (WS2812 not required)
• 330Ω resistor (if using single LED)
• Breadboard + jumper wires
• (Optional) Passive buzzer / small speaker
• (Optional) Transistor + MOSFET or relay if using higher-power LED strip
• Adult supervision for wiring/power

Safety notes

• Always power off Pi when wiring.
• If driving LED strips that use 5V >0.5A, use a separate power supply and common ground.
• No open flames. Keep small parts away from younger children.

Wiring (simple single-LED version)

1. PIR Sensor has 3 pins: VCC, OUT, GND.

• VCC → 5V on Pi (pin 2 or 4) or 3.3V (pin 1) depending on sensor spec (HC-SR501 typically runs on 5V — check module). If it needs 5V, use 5V; many work with 3.3V but confirm.
• GND → any Pi GND (pin 6).
• OUT → GPIO 17 (physical pin 11) — you can choose another free GPIO.

1. LED:

• LED long leg (anode) → 330Ω resistor → GPIO 27 (physical pin 13).
• LED short leg (cathode) → GND (pin 9).

1. (Optional buzzer) → GPIO 22 via resistor → GND.

Make sure grounds are common.

GPIO pin reference used above: PIR → GPIO17, LED → GPIO27, buzzer → GPIO22. You can change these but update the code.

Software setup (one-time)

1. Boot Raspberry Pi with Raspberry Pi OS. Make sure it’s updated:

sudo apt update && sudo apt upgrade -y

2. Install Python libraries (gpiozero is included in Raspberry Pi OS, but ensure latest):

sudo apt install python3-gpiozero python3-pip -y
pip3 install requests   # only if you add phone notifications later

Python code (easy, kid-friendly)

Save as smart_nightlight.py.

#!/usr/bin/env python3
# smart_nightlight.py
# Smart Night Light using PIR motion sensor and LED (gpiozero)

from gpiozero import MotionSensor, LED, Buzzer
from signal import pause
from time import sleep

# Pin setup (update if you wired differently)
pir = MotionSensor(17)   # PIR OUT -> GPIO17
led = LED(27)            # LED -> GPIO27 (via resistor)
# buzzer = Buzzer(22)    # Optional: Uncomment if using buzzer on GPIO22

# Behavior parameters
ON_TIME = 30  # seconds to keep light on after motion

print("Smart Night Light ready. Waiting for motion...")

def motion_detected():
    print("Motion! Turning light ON.")
    led.on()
    # buzzer.beep(0.1, 0.1, 2)  # optional short beep
    # Wait while motion persists, then countdown
    start = 0
    # keep the LED on while sensor is active
    while pir.motion_detected:
        sleep(0.5)
        start += 0.5
        if start > 60:  # safety break if sensor sticky
            break
    # after motion stops, keep LED for ON_TIME seconds
    print("Motion stopped — keeping light for {} seconds.".format(ON_TIME))
    sleep(ON_TIME)
    led.off()
    print("Light OFF. Waiting for motion...")

# Attach event
pir.when_motion = motion_detected

try:
    pause()  # wait forever, events will trigger
except KeyboardInterrupt:
    print("Exiting, cleaning up.")
    led.off()
    # buzzer.off()

How to run:

python3 smart_nightlight.py

What kids learn

• How sensors detect real-world events (PIR detects infrared from moving warm bodies).
• How to control hardware (GPIO → LED).
• Basic Python programming (functions, loops, libraries).
• Debugging and problem solving (why LED might not light, wiring issues).

Troubleshooting (quick)

• Sensor stuck HIGH: check VCC voltage (3.3V vs 5V compatibility) and sensitivity jumper on PIR.
• LED not lighting: check resistor and polarity; test LED by connecting briefly to 3.3V through resistor.
• Code permission error: run with python3 and ensure gpiozero installed.

Variations / extensions (pick one or more)

• Add ambient light sensor (LDR) so the night light only turns on at night.
• Use a small RGB LED and make color change modes.
• Send a notification to phone via IFTTT or webhook when motion detected (requires internet & requests library).
• Add a PIR + camera: take a quick photo (Pi Camera) when motion is detected (adult permission).
• Build a small case with cardboard and decorate it — STEAM craft + coding!

Short list of other simple kid projects for Raspberry Pi Model B

1. Retro game console with RetroPie (plays old-school games).
2. Weather station (temperature + humidity sensor) — displays on small LCD.
3. Music player / Jukebox controlled by buttons.
4. LED matrix message board (scrolling text).
5. Simple web-controlled LED (control light from phone).