pxt-calliope/olddocs/js/lessons/screen-wipe/activity.md

# screen wipe activity

Clear the screen by pressing buttons on the @boardname@.

### ~avatar avatar

This activity will teach how to clear the screen by pressing button ``A`` on the @boardname@.

### ~

You can use the `basic->clear screen` function to turn off all the LED on the screen. Let's illustrate this concept with a small script where the user has to press the button ``A`` to turn off the screen. Let's start by adding the code to show an animation.

```
basic.showAnimation(`
# # # # # # # # # # . . . . . . . . . .
# # # # # # # # # # . . . . . . . . . .
. . . . . # # # # # # # # # # . . . . .
. . . . . # # # # # # # # # # # # # # #
. . . . . . . . . . . . . . . # # # # #
`, 400) // ***
```

We add another line of code that registers an **event handler** on the `input->on button pressed(A)` and calls `basic->clear screen`.

```
basic.showAnimation(`
# # # # # # # # # # . . . . . . . . . .
# # # # # # # # # # . . . . . . . . . .
. . . . . # # # # # # # # # # . . . . .
. . . . . # # # # # # # # # # # # # # #
. . . . . . . . . . . . . . . # # # # #
`, 400)
input.onButtonPressed(Button.A, () => {
    basic.clearScreen() // ***
}) // ***
```

Run the script in the simulator or on the @boardname@ to see how this works!

### ~avatar boothing

Excellent, you're ready to continue with the [challenges](/lessons/screen-wipe/challenges)!

### ~