Scratch+Coordinate+Plane

=Scratch LESSON #4 Coordinate Plane =

** Purpose: ** This lesson introduces the coordinate plane. **Essential Question:** How do we put the a sprite in a specific location on the coordinate plane?

** The Coordinate Plane: ** The connection between geometry and algebra is the coordinate grid. A grid can be shown on a plane. An ordered pair will represent a point in the plane. A plane has two dimensions, which is why points are represented by two values. The first coordinate is called the **abscissa** and moves left or right. The second coordinate is called the **ordinate** and moves up or down. It is important to use the correct order (abscissa, ordinate). The ordered pair (0, 0) is called the **origin**. In Scratch, the cat’s home location is the origin. In this lesson, the canvas was changed to a grid by selecting the xy-grid backdrop. ** New Command **    Moves the sprite to the (//x, y//) point in the coordinate plane. The default values are the origin. Figure 1 shows the code to draw a rectangle. Figure 2 shows a grid in the graphics window. Segments were drawn from the point (200, 150) to points in each corner of the grid in a counter clockwise direction. Recall that the ordered pair moves horizontally the amount designated by the first coordinate (//x//), and moves vertically the amount designated by the second coordinate (//y//). Moves the sprite slowly from a location to a new point This example uses a 3 second time span. Figure 3 shows the code to draw green line segments from the origin to five different points in the coordinate plane. Figure 4. Graphic for this set of code. These segments are called vectors in a later lesson. TASK 1: Experiment with the go to and glide to commands by predicting where the sprite will be in the coordinate plane. TASK 2: Experiment moving the sprite with only the abscissa and ordinate commands. TASK 3: What is a quadrant in the coordinate plane?
 * New Command **