Sharpie Water-Based markers (formerly called Sharpie Poster Paint) are great for marking glass, chalkboards, mirrors and especially good for poster projects in school.
If you like Posca, you'll like the Sharpie Water-Based Paint Marker- the ink is very similar.
Vibrant color stands out on light and dark surfaces. Exceptional for marking windows with advertisements. Will wash off non-porous surfaces like glass with window cleaner. Non-toxic and acid-free. Safe for use by children.