# Lesson 13 Extra *extra* Challenge

#1

So I am thinking of having the students complete the extra challenge that involves keeping the red square from leaving the screen. I get the general solution to that using an and boolean.

However, as an additional challenge I was going to have them see if they can figure out how to keep the whole rectangle on the screen. Best I can figure out is you should test for 25, 25, 375, 375 and I believe this works. But I am struggling to figure out how I would explain why that is to students. Has anyone considering giving the students this type of challenge. I feel like if this was a game you wouldn’t want any part of the character in this case the rectangle to leave the screen. So this could be a good key learning thing for the students. I have attached my code that accomplishes this, but I am really struggling with why it is 25, 25, 375, 375. I would think it would be 50,50,350,350. I hope this makes sense and isn’t confusing.

// Create a sprite
var sprite = createSprite(200, 100, 50, 50);
sprite.shapeColor = “red”;

function draw() {
background(“white”);

// Move the sprite in the direction of the arrow keys
// But make sure it doesn’t go off the screen
if (keyDown(“up”) && sprite.y > 25) {
sprite.y = sprite.y - 5;
}
if (keyDown(“down”) && sprite.y < 375) {
sprite.y = sprite.y + 5;
}
if (keyDown(“left”) && sprite.x > 25) {
sprite.x = sprite.x - 5;
}
if (keyDown(“right”) && sprite.x < 375) {
sprite.x = sprite.x + 5;
}
drawSprites();

}

#2

NVM I figured it out. The shape is drawn from the center point that is why. Also this was posted in the wrong forum it was supposed to be for lesson 13 sorry.

#3

Ben,

No worries! Thank you for posting the problem solving steps, this will help others that might have the same question in the future. Thanks!