C to D is one whole step due to the black key in between them. E to G is a whole step and a half step there are 2 keys between them.
The Pentatonic Scale can be thought of as - whole step - whole step - whole step and a half step- whole step - whole step and a half step
Remember this pattern. WW3W3
Another way to think of the notes is in numbers - the first note C=1 and the second note D=2 and the third note E=3 and the fifth note G=5 so on.
Please have a look at Diatnic Harmony to see how the numbers way is the best in the end.
Here are some books about The Pentatonic Scale that are rated very well.
more soon!
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