Other tools you should consider as well as Flipgrid are:
Discussion Board: A discussion board should be used for short-question-and-answer-style collaboration between students.
Blog: A blog is an online journal that can include links to resources, multimedia as well as text in it's entries. Each student's blog can be viewed by other course members and commented on.
Journal: A journal is a private blog for communication between the teaching staff and individual students (or groups). Journals can not be seen or commented on by other students (or other groups) in the course.