Basic Elements Unit #2: Major Key Signatures
There are actually two different ways to think about your scales, and a good musician can use both. In the previous unit we learned the intervallic shape
major scale, and now we will memorize the contents of scales by learning their key signatures
This is covered in detail on Printout #2: Key Signatures.
The circle of fifths is a method for organizing every possible key signature.
In the beginning, I'd focus on memorizing what I call the "easy" keys, which are on the top half of the circle, from 3 flats to 3 sharps. Here's a worksheet you could use to practice that.
You should also practice writing out the scales from memory on a blank sheet of music paper, and playing them on your instrument.
If you want to try to recreate the entire circle of fifths from memory, I've got a blank circle in treble clef and bass clef.
Extra Practice for PC or Mac
Once again I recommend the java-based quizzer
at emusictheory.com. To practice this lesson you'll want to change the settings to "Ask only major keys" and "Do not ask for relative key."
Extra Practice for iPhone/iPad
($5) is a nice app that packs in tutorials and quizzes on a whole range of theory topics, including your key signatures.
There is also the free Key Signature Quiz which is decent.