As a FORMER semi pro artist, classified as 'abstract realism' (hey, thirty years ago you could find T-shirts with my art on them in truck stops across Oklahoma and Texas, I had local exihibitions and sold stuff across Oklahoma, Texas, and Colorado, but unfortunately pretty much told folks to go to h*ll when they told me what they wanted me to draw or paint) I shall critique your work. I like it, good job. (I'm named for your subject so that might sway my opinion a little.) Good technique. The eyes are always the hardest things to get right in a portrait, and you've done well on those. Your teacher probably wanted you to draw General Lee as there's more character in his face than Jackson's, and it would challenge your abilities, and makes for a better drawing. Once again, good job, keep it up, and you get an A+.