Yesterday, I posted a video in which I demonstrated how to impose a time limit on a Google Form. In response to that post someone on Facebook asked me if there was a way for students to save their progress on a Google Form and come back to finish it later. Unfortunately, there is not an easy way to do that. My suggestion is to break-up long tests into multiple Google Forms. At the end of each Form include a link to the next Form in the series. For example, instead of giving one twenty question Form to students I might give them two Forms containing ten questions each. In the video embedded below I demonstrate how to do this.
For more Google tools tutorials, check out my playlist of more than 80 Google tools tutorials.