When Okta swims into circle select an angle measurement by clicking on a bubble. This will aim the pie launcher. To throw the pie drag back on the crab and release. The further you drag the crab, the longer the distance the pie flies.
You can choose to use measurements in radians, degrees or mixed from the bottom left corner. A game timer is located in the top left corner to show you how much more time you have. A shot timer is located in the top right corner to show you how much time is left for the current shot.
The HINT button will show an overlay of measurements in degrees and radians. See if you can figure out the angles without using it!