The Guitar Scaler is truly the "Swiss Army Knife" for learning scales.
It contains a case and its multi-scale slider. This slider show the 3 most popular scales : pentatonic scale, major and natural minor scale and blues scale. A simple three color coding system identifies them.
The root notes are clearly represented.
The black notes correspond to the pentatonic scale.
Black + Red notes correspond with the heptatonic scale.
Black + blue notes correspond to the blues scale.
Turning the slider, you select the major or minor mode.
Move the slider in the case so as to show the desired key C, C#, D, etc.