1.3 XY Grid

Standards

• CSTA 1B-AP-13: Decompose problems and subproblems into parts to facilitate the design, implementation, and review of programs.

CSTA

TEACHER GUIDANCE:

Student knowledge of the cartesian X,Y Grid is useful but non-essential.

In scratch, when you drag a sprite on the stage and release, the new (X,Y) location of the sprite is updated all commands.

So if students move a sprite to it's initial position, then grab a goto command it will have the updated positional location information.

If students then move this sprite to it's final location and grab a glide command, glide will be updated with the final location information.

Students use blocks from the blue Motion category in Scratch to complete this assignment.

Set blocks set an absolute location on the coordinate grid in Scratch; "go to" is another version of the "set" blocks.

• Setting x to 100 will move the sprite to the exact location of x=100 on the coordinate grid.

Change blocks change the location relative to where the sprite currently is.

• Changing y by 10 will move the sprite 10 units up; this can be performed multiple times, changing the sprite's location until it reaches the edge of the coordinate grid.

Agenda

• Review the XY Coordinate grid. ( see note in teacher guidance).

• Watch this video on the X and Y axis in Scratch: The X-Axis and the Y-Axis (1:50)

• Students begin working through the challenges on student handout

• Either independently or as a whole class, students watch this video after completing steps 1-6 on the worksheet: Set and Change with X and Y Position (2:28)

Discuss the following questions:

• What is the difference between the set blocks and the change blocks?

  • What blocks will move the sprite to certain x,y position?