Something that we have trialled quite recently, on our optional fieldtrips, is to allow students to submit their work individually or as part of a group.
This is quite an interesting approach because, on the one hand, with a group you can pull ideas together and often work submitted as a group get a better grade than individual work. However, students with anxiety can have a lot of concern around group work (such as ‘what happens if people in my group pull my grade down’, for example), especially if they are high achievers. Thus far the feedback on this has been positive. It does make workload management trickier as you do not know exactly how many submissions you are going to get.