Why is it every time I look these up they are somewhat different? They say there are 5 pentatonic shapes, but different books, websites and videos have small changes .. The only one I have found to be consistent is the Am shape, which is always .....5-8 ..... 5-7..... 5-7 ..... 5-7 ..... 5-8..... 5-8 ..... but the others seem to vary------- SO WHICH ONES ARE CORRECT AND WHICH ONES SHOULD I COMMIT TO MEMORY????