pxt-calliope/docs/lessons/screen-wipe/challenges.md
2016-06-01 20:53:46 -07:00

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# screen wipe blocks challenges
Coding challenges for screen wipe.
## Before we get started
Complete the [screen wipe](/lessons/screen-wipe/activity) activity and your code will look like this:
```blocks
basic.showLeds(`
# # # # #
# # # # #
. . . . .
. . . . .
. . . . .
`)
basic.showLeds(`
# # # # #
# # # # #
# # # # #
# # # # #
. . . . .
`)
basic.showLeds(`
. . . . .
. . . . .
# # # # #
# # # # #
. . . . .
`)
basic.showLeds(`
. . . . .
. . . . .
. . . . .
# # # # #
# # # # #
`)
input.onButtonPressed(Button.A, () => {
basic.clearScreen()
})
```
### Challenge 1
Create an event handler for Button B.
```blocks
basic.showLeds(`
# # # # #
# # # # #
. . . . .
. . . . .
. . . . .
`)
basic.showLeds(`
# # # # #
# # # # #
# # # # #
# # # # #
. . . . .
`)
basic.showLeds(`
. . . . .
. . . . .
# # # # #
# # # # #
. . . . .
`)
basic.showLeds(`
. . . . .
. . . . .
. . . . .
# # # # #
# # # # #
`)
input.onButtonPressed(Button.A, () => {
basic.clearScreen()
})
input.onButtonPressed(Button.B, () => {
})
```
### Challenge 2
Replay the animation when the "B" button is pressed placing the `show LEDs` block on the canvas.
```blocks
basic.showLeds(`
# # # # #
# # # # #
. . . . .
. . . . .
. . . . .
`)
basic.showLeds(`
# # # # #
# # # # #
# # # # #
# # # # #
. . . . .
`)
basic.showLeds(`
. . . . .
. . . . .
# # # # #
# # # # #
. . . . .
`)
basic.showLeds(`
. . . . .
. . . . .
. . . . .
# # # # #
# # # # #
`)
input.onButtonPressed(Button.A, () => {
basic.clearScreen()
})
input.onButtonPressed(Button.B, () => {
basic.showLeds(`
# # # # #
# # # # #
. . . . .
. . . . .
. . . . .
`)
basic.showLeds(`
# # # # #
# # # # #
# # # # #
# # # # #
. . . . .
`)
basic.showLeds(`
. . . . .
. . . . .
# # # # #
# # # # #
. . . . .
`)
basic.showLeds(`
. . . . .
. . . . .
. . . . .
# # # # #
# # # # #
`)
})
```
### Challenge 3
Show an animation that scrolls back up when you press button "B".
* tap the *run* button to view your final product!