Crate World is a free app for the iPad that is designed to help students develop math skills for number lines and coordinate planes. It has five levels for students to work through beginning with simple number lines and ending with finding the equation of a line starting with two points.

Each level has multiple activities focused on a specific skill. For instance level one or Apprentice one works on having students develop their skill using both horizontal and vertical number lines. They work with both positive and negative numbers. Occasionally, they throw in an absolute value.

The first few exercises have students locate the red crate x units from the green one both horizontally or vertically. Other times, students are required to place a crate in a specific location or place it at the answer to a problem. The last part of this level requires the student to find the distance between two crates.

Level two or Apprentice 2 are required to move crates on a 10 by 10 grid with numbers from -10 to 10 both horizontally and vertically. The level begins by having students identify the coordinates of a crate. Then they must locate a point on the graph, identify the rise and run to get from one crate to another, move crates and then find distance.

Level three or Apprentice 3 begins by having student identify the equation for a vertical or horizontal line. Moving on to identifying slope, locating a crate on a point of the line given so the line visually appears, identifying the equation for a given line, finishing with solving for the horizontal or vertical line.

Level four or Apprentice 4 has students continuing with what they've done but they are solving for missing numbers in a variety of situations. They have to solve for y, b, x, and m. Each one is a different activity and the level culminates in finding the slope between two crates.

Level five or Apprentice 5 takes it all one step further. It has students learn to rewrite equations from standard form to slope - intercept form, square of numbers, square roots, distance using the distance formula, finding slope from two points, and determining which set of coordinates will make the equation true.

If the answer is not correct, the student receives immediate feedback by either having the crate move to the next button to try again or it will say try the next problem. The app is free and provides multiple opportunities for students to practice all aspects of finding and using linear equations.

I like the way this is set up more as a game than an instructional instrument. I also like the way the first level is predominately focused on helping students learn to use horizontal and vertical number lines. Many of my students are weak in that area and I can get them playing it much earlier in the semester. I look forward to using it in class this fall.