NASA’s entire online media library is open to the public and all items are copyright free. With 140,000 images alone, you can hear sounds, and watch videos and even download and use them any way you’d like!
https://alldigitalschool.com/ It has 2000+ educational resources (apps/tools/websites/ebook/videos etc..) for all school levels (k-12) organised by subject, year level, type as well as price (mostly free ones). There is also a special filter in the directory so that only resources made free by their owners due to the Covid-19 outbreak will be listed
Teach yourself tech! Free technology resources for K-12 students from West Michigan Tech Talent to do at home.