caveman making a wheel
You don't always have to re-create the wheel.

There are many amazing resources available for free online.
You just need to spend some time finding appropriate ones for your lesson.

Try some of these:

Youtube.com In the search box on their page, type in keywords that pertain to your lesson (Caution--these videos range in quality. Many are student projects that they have uploaded. Be sure to check them for appropriateness and accuracy).

Merlot.org Peer-reviewed teaching and learning materials you can use

Cnn.com or other websites with current events

Khan Academy khanacademy.org ("Learn almost anything for free!")
In the search box on their page, type in keywords...

Browse content at URLs (weblinks) that are relevant to your discipline

Does your textbook have an accompanying website with resources online?