# 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](/js/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.  ****************************** ## 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)