handwritten abstract text seamless patterns set, school university blackboards, some text with mistakes and misprints

abstract art backdrop background black blackboard blackboards board calligraphy chalk chalkboard cursive decor design dirty document doodle drawing drawn education graphic grunge hand handwrite handwriting handwritten illustration isolated letter misprint misprints mistake mistakes monochrome old paper pattern patterns pen retro school science script seamless set silhouette sketch some text texture type university unreadable vintage wallpaper word write