XY Coordinate Plane

1. Understanding the Coordinate Plane

Imagine the Scratch stage is like a big map, and we can tell our sprites exactly where to go on this map using two numbers. These numbers are called coordinates!

Let's explore the Scratch stage:

1. The center of the stage is (0, 0).

2. Moving right increases the X value, moving left decreases it.

3. Moving up increases the Y value, moving down decreases it.

4. The stage goes from -240 to 240 in X, and -180 to 180 in Y.

Let's Practice!

Try to guess where these coordinates would place a sprite:

• (100, 50)
• (-150, 100)
• (0, -100)

Now, open Scratch and use the "go to x: _ y: _" block to check your guesses!

2. Moving Sprites with Coordinates

Now that we understand coordinates, let's make our sprites dance around the stage!

We'll use these blocks:

Let's make a sprite move in a square:

1. Drag out a "when green flag clicked" block to start your script.

2. Add a "change x by 100" block. This moves the sprite right.

3. Add a "wait 1 second" block to see the movement.

4. Now add "change y by 100" to move up.

5. Can you figure out how to complete the square?

Challenge: Make a Triangle!

Using the "change x by" and "change y by" blocks, can you make your sprite move in a triangle shape? Remember, you might need to use negative numbers to move left or down!

3. Exploring "Move" and "Glide"

We've seen how to teleport our sprites and move them step by step. Now, let's make their movements smooth and fancy!

New Blocks:

Let's make a sprite glide smoothly:

1. Start with a "when green flag clicked" block.

2. Add a "glide 2 secs to x: 100 y: 100" block.

3. Now add "glide 2 secs to x: -100 y: -100".

4. Click the green flag and watch your sprite move!

Fun with Random Gliding

Let's make our sprite move to surprise locations:

1. Use a "forever" loop to repeat the action.

2. Inside the loop, add "glide 1 secs to random position".

3. Run your script and watch the sprite zoom around!

Try changing the glide time to make it faster or slower. What happens?

4. Fun Projects and Homework

Great job learning about coordinates and movement! Now, let's put your skills to the test with some fun projects.

Homework Challenge: Maze Explorer

Create a maze on the Scratch stage and program a sprite to navigate through it using the arrow keys.

1. Draw a maze backdrop or use one from the Scratch library.

2. Create a sprite that will explore the maze.

3. Use "if" blocks with "key pressed" conditions to move the sprite.

4. Use the "touching color" block to detect if the sprite hits a wall.

5. Add a starting point and a finish line to your maze.

Remember to test your maze and make sure it's possible to complete!

Extra Credit: Coordinate Art

Create a drawing by programming your sprite to move to specific coordinates. Try to draw a simple picture or write your name!

1. Use the "pen down" block to start drawing.

2. Use "go to x: _ y: _" blocks to move your sprite.

3. Experiment with different colors and pen sizes.

Share your coordinate art with the class next time!