I have created a "Paragraph of the week" assignment in Canvas using Google Slides as an External Tool submission. I need students to write on a slide eon each of four days and then submit the assignment at the end of the week. How can I make this happen?
If you have a template of the four slides, you should be able to set up an assignment to accept the google cloud submission at the end of the four days: https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-create-a-cloud-assignment-with-a-Google...
I'm not sure that you will be able to track whether they write one paragraph a day or 4 paragraphs on the last day (as my students would).
Another option (if you would like students to see and interact with each other's paragraphs) is to have a weekly discussion, and require a post on each of 4 days (you would see every post and its submission date in speedgrader.) Or a daily discussion, if the topic changes every day. In that case you can also set it to require students to post before they can see the posts of other students.
Journal assignments have been suggested in the idea forum in the past as a way to do this without sharing submissions with the class. There are a number of suggestions in this conversation, including one that will give you time-stamped submissions without students seeing each other's work. You can put each student in their own group within a group-set and create a group discussion for the group-set. The result will be one discussion (for you) but the students in the forum will each only see and interact with you. This video details the steps https://youtu.be/PKkQij-Vzok