Discovery Education STEM Connect is a great resource for teachers looking for more resources for teaching Science, Technology, Engineering, and Math.
There are lesson plans, example projects, and resources for each area of STEM and they are divided by Grades 6-8 and 9-12.
The resources are very useful and easy to implement.
You do need an account to account to get to this page, but you can sign up for a free educator account (which also gives you access to the Discovery Educator Network which has even more resources).
Another Discovery Education STEM resource is the Siemens STEM Academy. This also has a great many resources for teaching STEM topics, including resources, links, and lesson plans. There are also professional development opportunities and Siemens Foundation grants and opportunities.
Explore them and see what they have to offer.