HI @GretchenRipple 

It's very possible.  After students select the first photo to upload, they just need to click, "Add another file" before they click submit.  They can upload many files, I'm not sure what the limit is. I've had students submit three or four at a time. 

See this guide. 

https://community.canvaslms.com/t5/Student-Guide/How-do-I-upload-a-file-as-an-assignment-submission-...