Common Core State Standard
Recognize angles as geometric shapes that are formed wherever two rays share a common endpoint, and understand concepts of angle measurement.
The balloons are coming in from all directions. Figure out the direction in degrees that the cannon needs to point and pop the balloons before they get too close.
Plug in the correct measurement in degrees to direct the orbiting cannon crew on where to fire. Prevent the aliens and meteorites from reaching Earth. Buy upgrades to help get through all of the levels.