int ledPins[] = {
  2, 3, 4, 5, 6, 7, 8, 9, 10, 11
};   // an array of pin numbers to which LEDs are attached


void setup() {
  pinMode(A0, OUTPUT);
  for (int Led = 2; Led < 12; Led++) {
    pinMode(Led, OUTPUT);
  }
  Serial.begin(9600);
}

void loop() {
  int sensorReading = analogRead(A0);
  int ledLevel = map(sensorReading, 0, 1023, 1, 12);
  
  Serial.println(ledLevel);
  for (int Led = 1; Led < 12; Led++) {
    if (Led < ledLevel) {
      digitalWrite(Led, HIGH);
    }
    else {
      digitalWrite(Led, LOW);
    }
  }
}