pxt-calliope/docs/reference/js/lessons/cascade/quiz.md

strobe lightquiz

Learn how to create a blinking LED script with a for loop.

Name

Directions

Use this activity document to guide your work in the light column cascade tutorial.

Answer the questions below while working on or after you finish the tutorial. Pay attention to the dialogs!

1. What is a for loop?

2. Consider the following code

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

If the rectangle below represents a board that is 5 LEDs wide and 5 LEDs tall, place an X approximately all the locations where the LED is lighted. Explain why the LED is lighted there.

3. Consider the following code

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

If the rectangle below represents a board that is 5 LEDs wide and 5 LEDs tall, place an X approximately all the locations where the LED is lighted. Explain why the LED is lighted there.

4. Consider the following code

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

If the rectangle below represents a board that is 5 LEDs wide and 5 LEDs tall, place an X approximately where the LED is lighted. Explain why the LED is lighted there.

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ANSWER KEY

Directions

Answer the questions below while working on or after you finish the tutorial.

1. What is a for loop?

Answers will vary. In general, for loop refers to the code that repeats for a fixed number of times. We specify the LED using x, y coordinates.

2. Consider the following code

for (let i3 = 0; i3 < 5; i3++) {
    for (let j3 = 0; j3 < 5; j3++) {
        led.plot(i3, j3)
    }
}

If the rectangle below represents a board that is 5 LEDs wide and 5 LEDs tall, place an X approximately where the LED is lighted. Explain why the LED is lighted there.

This code turns on specific LED. Plot turns on the specified LED on the LED screen. We specify the LED using x, y coordinates. The code lights on the LEDs

x - the x coordinate or horizontal position (0,1,2,3,4)

y - the y coordinate or vertical position (0,1,2,3,4)

3. Consider the following code

for (let i4 = 0; i4 < 3; i4++) {
    for (let j4 = 0; j4 < 3; j4++) {
        led.plot(i4, j4)
    }
}

If the rectangle below represents a board that is 5 LEDs wide and 5 LEDs tall, place an X approximately where the LED is lighted. Explain why the LED is lighted there.

This code turns on specific LED. Plot turns on the specified LED on the LED screen. We specify the LED using x, y coordinates.

x - the x coordinate or horizontal position (0,1,2)

y - the y coordinate or vertical position (0,1,2)

4. Consider the following code

for (let i5 = 0; i5 < 2; i5++) {
    for (let j5 = 0; j5 < 2; j5++) {
        led.plot(i5, j5)
    }
}

If the rectangle below represents a board that is 5 LEDs wide and 5 LEDs tall, place an X approximately where the LED is lighted. Explain why the LED is lighted there.

This code turns on specific LED. Plot turns on the specified LED on the LED screen. We specify the LED using x, y coordinates.

x - the x coordinate or horizontal position (0,1)

y - the y coordinate or vertical position (0,1)