Although you can learn how to construct chords and scales from memory there is an absolutely amazing tool for finding scales and chords on just about any fretted instrument, including guitars, basses, and mandolins.
This tool is the Chord and Scale Fret Finder tool from StudyBass.com.
What is also great about this tool is the ability to use alternate tunings such as open C and D.
Check out the print feature as well so you can play your scales and chord offline, or keep in your instrument case for quick reference.
Until next time keep up the good practice,