Student Instructions

velocityX

One way to move sprites in Game Lab is with the counter pattern. For example sprite1.x = sprite1.x + 1 moves a sprite by 1 pixel each frame of the draw loop. This pattern is so common that sprites have a velocityX property that does this for you.

Do This

• Drag a sprite.velocityX block directly below where your sprite is created.       ( Show me where )
• Write the name of your sprite in the block.
• Assign the velocityX property a value of 1.
• Run the code. What happens?
• Re-run the code giving the velocityX property a different value. What's changing?

Student Instructions

Moving Down

Here is a feather sprite that should be floating down the screen. If velocityX makes a sprite move to the right, can you find the block that will make the feather move down?

Do This

Find the block that will make the feather sprite go down the screen, and use it outside the draw loop.   ( Show me where )

Student Instructions

rotationSpeed

You've already learned how to make your sprite spin by using the rotation block. For example, when you wanted your sprite to rotate by two degrees each time it was drawn, you put sprite.rotation = sprite.rotation + 2 inside the draw loop.

Now, you can use rotationSpeed to make your sprites rotate by a certain amount each time they are drawn. If you want your sun to rotate by two degrees each time it's drawn, you can use sun.rotationSpeed = 2 before the draw loop, after you create your sprite.

Do This

Make the sun rotate by 3 degrees each time using the rotationSpeed block. ( Show me where )

Student Instructions

Controlling Speed

You used rotatationSpeed outside the draw loop to make your sprite rotate when your program started. You can also use rotationSpeed inside the draw loop to change the speed of the sprite during the game. For example, a sprite can start rotating when the user presses the space bar, and it will keep rotating until it's told to stop.

Do This

• Look at the if statement inside the draw loop that checks whether the space bar has been pressed. ( Show me where )
• Use the rotationSpeed block to make the color wheel start spinning when the user presses the space bar.

Student Instructions

Controlling Speed

Your code before the draw loop sets up the beginning of your game. Your code inside the draw loop controls how the game will change while it's being played. In this game, the helicopter bot starts off at the bottom of the screen, but when the space key is pressed, it flies up.

Do This

• Use an if statement inside the draw loop to check when the space bar is pressed.
• Use the velocityY block to make the sprite fly up when the user presses the space bar. The sprite should keep moving up even after you let go of the space bar.

Student Instructions

Student Instructions

Multiple Controls

As you saw in the last level, you can change the sprite's velocity with multiple if statements. In this program, the fish has three different types of movement, each of which should be controlled by its own if statement.

Do This

• Look at the three if statements inside the draw loop.

• Use a sprite.velocityX block inside each if statement to make the three following movements:

• If the user presses the right arrow key, move the fish to the right.
• If the fish gets to the right-hand side of the screen, move the fish to the left.
• If the fish gets to the left-hand side of the screen, stop the fish.

Student Instructions

Jumping

You now have all the blocks you need to make your sprite jump!

Just as you checked whether your fish was at the left edge, you'll need to check whether the frog is on the ground. If it is, it could either jump up or stay still, so you'll need one more if block to check whether the user has pressed the up arrow ( Show me where ).

You'll also need to check whether the frog has reached its highest point, and send it back down if it has.

Do this

• Find the if statement that checks whether the sprite is on the ground, and look at the if statement inside of it that checks whether the user has pressed the "up" arrow key. ( Show me where )
  • Use the velocityY block to make the frog jump up when the user presses the arrow key.
  • Use the velocityY block to make the frog stop moving otherwise.
• Add an if statement that does the following ( Show me where )
• Checks whether the frog sprite has reached its highest point.
• If so, use the velocityY block to make the sprite fall back down.

Student Instructions

Mushroom

Now you just need something for your sprite to jump over. This program already has a mushroom just past the right edge of the screen, but it needs to move toward your frog.

Do this

• Use the velocityX block to make the mushroom move left across the screen.

Hint: The mushroom should start moving at the very beginning of the game, and never change, so should it be inside or outside the draw loop?

Student Instructions

Looping

The game will be more fun if the frog can jump more than once. You can make the mushroom "loop" by checking whether it's moved past the left edge and moving it back to the right edge when it has.

Do this

• Find the if statement that checks whether the mushroom has passed the left edge. ( Show me where )
• Use the sprite.x block to set the mushroom's position back to the right edge if it has.