LINK TO SITE
Many high schools, colleges, and universities already use this tool for their long-distance education programs. Educators must register, but the students can sign in as Guests. This tool enables teachers to write, draw, or attach documents, and what makes it great is that it is LIVE, i.e. the student sees everything in real time just as the teacher is writing, drawing, or sending documents. Teachers and students can also take screenshots of ongoing lectures to save for future reference.
Features include audio, video, and chat. The 2-week free tryout has most features, but the full version is inexpensive, and there's a discount for annual subscriptions.