We developed www.learnclick.com for easily creating gap-filling and other types of quizzes. The tool is especially loved by language teachers. I recently used it myself while teaching my Korean brother-in-law English with Skype.

This is how it can be done: During a Skype or Zoom class take notes of areas where the student had difficulties and of mistakes he made. Based on that create a few example sentences. Using learnclick.com you can create a quiz with a few mouse clicks in minutes which you can then share with your student. You can also create a username for your student so that the answers he gives get recorded.

Your students will appreciate this type of review and it will help you as teacher to make lessons more individual, based on the students needs.

You can use an iframe code so that your students never have to leave your homepage as described here:
http://www.learnclick.com/site/embedhelp