One of those "unforgettable" moments for me as a piano student was when my first teacher taught me this little trick for remembering the sharp key signatures. I can still visualize her writing out the goofy letters on my notepad as she sat in the chair beside me and it has stuck with me ever since. The number of pencil strokes used to draw each of the letters (w/ a few clever adaptations like a rounded 1 stroke G and a pointy B) correlates with the number of sharps in each of the major key signatures). This method would be especially effective with a kinesthetic learner if you have them write the letters along with you. I am primarily a visual learner... so just watching her draw this mnemonic device has stuck with me for life.