There are many free stock photo sites that can be used for online learning. Here is a list of some of the best:

1. Pixabay

Pixabay is a great resource for finding free stock photos for online learning. They have a wide variety of photos and they are constantly adding new photos to their site.

2. Unsplash

Unsplash is another great free stock photo site. They have a wide variety of photos and they are constantly adding new photos to their site.

3. Freeimages

Freeimages is another great free stock photo site. They have a wide variety of photos and they are constantly adding new photos to their site.

4. ShutterStock

ShutterStock is another great free stock photo site. They have a wide variety of photos and they are constantly adding new photos to their site.

5. 500px

500px is another great free stock photo site. They have a wide variety of photos and they are constantly adding new photos to their site.