As a science teacher, NASA is an incredible resource for me. NASA has tons of great, free, educational resources that are also good for any subject.
NASA also has a speakers bureau that will provide engineers, scientists, and other professionals to speak to audiences around the country. You can also request an astronaut to come and speak to your class. It is free, but there are some conditions. It is an easy process.
Have some exciting, knowledgeable speakers come to your school, for free, and educate and motivate your students.
NASA Speakers Bureau
NASA - Find lots of great educational resources