Watch the Open Chord Vocabulary online guitar lesson by Susan Mazer from Hands On Guitar: Beyond Beginner
While you’re learning these open shapes it’s important to have the chord chart in front of you. Seeing the visual pictures always helps to solidify what you're learning. Once you're confident with the chords, try quizzing yourself by taking the chord chart away. Go through "A" - "A7" - "Amajor7" - "Am" - "Am7" in alphabetical order.