Tilt switch on A5 lights the LED on pin 8, on an Arduino Uno

// Tilt ball switch read on an analog pin: upright, the LED on pin 8 lights.
//
//   5V -> tilt switch -> A5 -> 220 ohm -> GND
//   pin 8 -> 220 ohm -> LED -> GND
//
// Inside the switch a metal ball rests on two contacts. Upright, the ball
// joins them and A5 sits at 5 V, so analogRead() gives about 1023. Tip it
// and the ball rolls away: the resistor pulls A5 down to 0. Anything over
// 1000 counts as closed.
//
// An analog pin reads a switch as well as a digital one does; this one just
// gives a number instead of HIGH or LOW. Click the switch to tip it.

const int TILT_PIN = A5;
const int LED_PIN = 8;

bool wasClosed = false;
bool first = true;

void setup() {
  pinMode(LED_PIN, OUTPUT);
  Serial.begin(9600);
  Serial.println("Mokxi Uno: tilt switch on A5, LED on pin 8");
}

void loop() {
  int reading = analogRead(TILT_PIN);
  bool closed = reading > 1000;
  digitalWrite(LED_PIN, closed ? HIGH : LOW);
  if (first || closed != wasClosed) {
    first = false;
    wasClosed = closed;
    Serial.print(closed ? "upright, A5 reads " : "tipped, A5 reads ");
    Serial.println(reading);
  }
  delay(20);
}