In a school setting, you are permitted to use copy-written resources in limited ways according to a legal doctrine called Fair Use.
Knowing about Fair Use can keep you out of trouble with the creators.
Copyright doesn't apply to everything. Under certain conditions, a resource may be entered into Public Domain, where anybody can use, in any way.
You can use public domain resources to make fliers, projects, and presentations.
A special form of copy-righting is Creative Commons Licensing. People who use CC licenses grant certain conditional privileges to users to share and adapt resources.
You can use CC resources to make projects, and presentations, and allow others to use and adapt your creations.
You can always ask the copyright holder for permission. (Here's guidance for doing that.) Feel free to take your questions to me or to post them on the Copyright Advisory Network.
Students need to learn about and respect the rights of creators (writers, coders, photographers, etc.) It's part of digital citizenship. It may motivate them to respect themselves as creators too.