Yes, you are correct that there are 5 major open scales: A, C, D, E, and G. However, B and F are not considered open scales because they require additional fingerings due to the absence of open strings. The open scales are popular among beginners due to the ease of playing open strings, but as you progress, you'll learn the fingerings for all major scales, including B and F. Keep up the good work in teaching yourself music theory!