Coordinates

When you want to specify a position in two-dimensional (2D) space, the most common way is to use x and y coordinates. There's a horizontal x axis and a vertical y axis. Any position can be referred to using a pair of numbers like this: (100,200). The first number is always the x coordinate; the second number is the y coordinate.

Most 2D coordinate systems have the x and y axes crossing, with position (0,0) squarely in the middle of the space. Kids are normally taught 2D coordinate systems where (0,0) is in the lower-left corner of the space, so that y numbers increase as you go up.

In programming (and thus in Bitsbox), position (0,0) is located in the upper-left corner of the screen. Here, y numbers increase as you go down. This is confusing at first, but we think it's important for kids to get used to the convention in programming as soon as possible.

The Bitsbox tablet screen is 768 pixels wide and 1024 pixels tall. The centerpoint of the screen is (384,512).