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docs/reference/js/lessons/night-light/activity.md

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+# night light activity
+
+change the brightness of the BBC micro:bit. #docs #tutorials #stepByStep
+
+### ~avatar avatar
+
+### @video td/videos/night-light-0
+
+Welcome! This tutorial will teach you how to change the brightness of the BBC micro:bit. Let's get started!
+
+### ~
+
+The brightness of the LED screen can be changed by using the `led->set brightness` function. This function takes a number between ``0`` (off) and ``255`` (full brightness).
+
+Let's build a little app that dims the screen when pressing button ``A``.
+
+Add the code `led->plot all` to turn on all the LEDs. Don't hesitate to run your code to see what happens.
+
+```
+led.plotAll() // ***
+```
+
+The screen starts with a 50% brightness value by default (128). Add a new line of code to set the full brightness (255) using `led->set brightness`.
+
+```
+led.setBrightness(255) // ***
+led.plotAll()
+```
+
+Add a new event handler for `input->on button pressed(A)` and add the code to set the brightness to `64`.
+
+```
+led.setBrightness(255)
+led.plotAll()
+input.onButtonPressed("A", () => {
+    led.setBrightness(64) // ***
+}) // ***
+```
+
+### ~avatar boothing
+
+Excellent, you're ready to continue with the [challenges](/microbit/lessons/night-light/challenges)!
+
+### ~
+