pxt-calliope/docs/reference/js/lessons/strobe-light/quiz.md

# strobe light quiz

Learn how to create a blinking LED script with a for loop. #LED #screen #plot #docs

## Name

## Directions

Use this activity document to guide your work in the [strobe light tutorial](/microbit/lessons/strobe-light/tutorial)

Answer the questions while completing the tutorial. Pay attention to the dialogues!

## 1. What is a for loop?

## 2. Draw which LEDs are ON after running this code

```
for (let i = 0; i < 5; i++) {
    for (let j = 0; j < 5; j++) {
        led.plot(i, j)
    }
}
```

![](/static/mb/empty-microbit.png)

## 3. Draw which LEDs are ON after running this code

```
for (let i1 = 0; i1 < 3; i1++) {
    for (let j1 = 0; j1 < 3; j1++) {
        led.plot(i1, j1)
    }
}
```

![](/static/mb/empty-microbit.png)

## 4. Draw which LEDs are ON after running this code

```
for (let i2 = 0; i2 < 2; i2++) {
    for (let j2 = 0; j2 < 2; j2++) {
        led.plot(i2, j2)
    }
}
```

![](/static/mb/empty-microbit.png)