Highly recommend
https://EasyVirtualChoir.com, super easy to use, and it is FREE! The software aligns audio/video tracks automatically and generates virtual choir videos instantly. Users have created videos for choir, band, chamber music, virtual rehearsal, online music teaching, choir dance, audition, recital, singing with sign language, drama practice, skit etc., or simply for fun with friends and family. Educators have used it to integrate music, teacher instructions and student participation into one video. It’s a great visualization tool and virtual platform combined, especially useful for online classrooms. The entire process is so intuitive, simple and fast for both teachers and students, that many k-12 school teachers got a video created with 15-40 kids after just one class period. Remote music classes and online rehearsals have become so much easier with this software, which has made teachers thrilled, students delighted, and parents pleased. Hope this free service will help your students too!