Student Instructions

When to Provide an "Else"

The else clause is useful when you want the program to do one thing when your condition is true, and a different thing when your condition is false.

Do This

Click "Run" to see the swarm of bees created for you and a flower on the left side of the screen. Make the swarm of bees appear when the mouse is near the flower (on the left side of the screen) and disappear when the mouse is away from the flower (on the right side of the screen). Look at the example on the right.

• Add an if else statement after you update the position of the bees.
• In the input of the if use a boolean to check if the x position of the mouse is on the side of the screen with the flower.
• Set the visible property of each bee inside both the if and else statements appropriately to make the bees only show near the flower.

Student Instructions

Reverse the Gears

The gears are back. They already spin when you press the space bar, but now you'll want to reverse them when you're not spinning it.

Do This

• Makes the gears spin opposite of the direction that they do when the space bar is pressed.

Student Instructions

Mouse X and Y

One of the simplest ways to take input is to just make a sprite follow the user's mouse position. You can get the x and y location of the mouse using World.mouseX and World.mouseY. This follows the pattern you learned with sprite properties. World is the name of the object. mouseX and mouseY are the names of the properties.

Do This

You are going to make a bee sprite follow the mouse around the game area.

• The bee image is already loaded in the animation tab for you.
• Create a bee sprite that draws in the center of the window.
• Inside the draw loop update the position of the sprite to the position of the mouse:
  • Set the x position of the sprite to the value of World.mouseX.
  • Set the y position of the sprite to the value of World.mouseY.
• Run the program to test that it works.

Student Instructions

Random Around Point

Now that you can make the bee follow the mouse, lets make a bee fly around the mouse as shown in the picture on the right. In order to do this, you will need to add a random amount between -50 and 50 to the mouseX or mouseY.

Do This

You already have a bee sprite that follows the mouse.

• Update the x and y location to be randomly close to the mouse.
  • Add a random number between -50 and 50 to the World.mouseX and World.mouseY.
• If necessary, use the World.frameRate block to slow down the animation and find the best frame rate.

Challenge: Add 3 more bees that follow the mouse in the same way to make a swarm of bees.

Student Instructions

Student Instructions

Student Instructions

Mouse Clicks

Keypresses are great, but sometimes you want users to interact through mouse clicks. There's a new block called mouseDown which, similar to keyDown, checks whether the left or right mouse buttons is being pressed. If you are using a computer with a mouse or trackpad that has only one button, you'll want to always use mouseDown("left").

Do This

Here's a program that drops a balloon down the screen - you're going to program the mouse button to raise the balloon back up while it's clicked.

• Add an if else statment that checks for mouseDown.
• Inside the conditional, move the balloon up one pixel if the mouse is down. Otherwise, move the balloon down.

Hint: You'll need to move the code that drops the balloon for this to work - you only want it to run if mouseDown is false

Challenge: Can you make the balloon drift randomly to the left and right as it rises and falls?

Student Instructions

Responding to a Single Click

Earlier we learned that keyWentDown and keyWentUp can be used to respond to a keypress a single time. The blocks mouseWentUp and mouseWentDown allow you to do that for the mouse!

Do This

Let's make a simple game that counts how many times you've clicked. We've already provided a variable clicks that you can use to track how many times the user has clicked.

• Add a conditional that checks if the mouse went down.
• Inside your conditional, add to the clicks variable.

Challenge: Can you add a sprite that responds to mouseWentDown as well? Add an image of your choice and increase the sprite's size each time the mouse is clicked.

Student Instructions

mouseDidMove

We can also use Boolean expressions to check whether or not the mouse has moved. The mouseDidMove block will return false if the mouse is still, but true if the mouse has been moving.

Do This

Right now, this program just displays a salt shaker sprite. You'll need to use mouseDidMove so that you can "shake" the salt by moving the mouse back and forth.

• Add a conditional that checks if mouseDidMove.
• If the conditional is true, rotate the salt sprite randomly to the left or right.

Challenge: Can you keep track of how many times the mouseDidMove shakes the salt, and then rotate it right side up after 100 shakes?

Student Instructions

Challenge: Checking for Multiple Conditions

Check with your teacher before taking on this challenge.

So far we've looked at a lot of ways to check if a single condition is true, but often a program needs to check the state of many conditions simultaneously before making a decision. For this challenge, let's assume the following scenario:

• The sprite should move up, down, left, and right if the corresponding arrow key is pressed.
• The sprite should not go all the way off the screen in any direction.

Do This Together

Before you tackle writing this program, you'll need to figure out how to check multiple conditions at once.

• Brainstorm with your neighbors ways you might check for more than one condition.
• Share back with other classmates so you can see other potential approaches.
• Explore the toolbox for blocks that might help (pay extra attention to the Math and Control drawers).
• Program your proposed solution.
• Test your program to make sure it's actually checking all of the conditions you intended.

Student Instructions

Free Play

Use what you've learned to create whatever you like. When you're finished, you can click to send your creation to a friend, or to send it to your Projects Gallery.