pxt-calliope/docs/reference/js/lessons/rotation-animation/quiz-answers.md

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2016-03-26 00:47:20 +01:00
# rotation animation quiz answers
Learn how to create a rotating image with a while loop. #image #loop #while #docs
This is the answer key for the [rotation animation quiz](/microbit/lessons/rotation-animation/quiz).
## 1. What is a "global variable"?
Answers may vary. A global variable is a place where you can store data so that you can use it later in your code.
## 2. Consider the following directions
Write the code to create a **global variable** called `foo` that stores a boolean and initialize it to **false**.
```
rotating = true
```
## 3. Consider the following code
```
while (rotating) {
}
```
Explain what this line of code does.
<br/>
It is a **while** loop that will be executed only if the **global variable** called `rotating` is **true**.
## 4. Consider the following code
```
basic.showAnimation(`
# . . . . . . # . . . . . . # . . . . .
. # . . . . . # . . . . . # . . . . . .
. . # . . . . # . . . . # . . # # # # #
. . . # . . . # . . . # . . . . . . . .
. . . . # . . # . . # . . . . . . . . .
`, 400)
```
If the rectangle below represents the BBC micro:bit, shade the areas that will be displayed. Explain why that particular area is shaded.
![](/static/mb/lessons/rotation-animation-0.png)
![](/static/mb/lessons/rotation-animation-1.png)
![](/static/mb/lessons/rotation-animation-2.png)
![](/static/mb/lessons/rotation-animation-3.png)
Show animation will show a series of image frames on the LED screen, pausing the specified time (400 milliseconds) after each frame