Teachers Pay Teachers is a great place to find Lessons and Activities for any subject you are trying to teach. These resources can be found by grade level, subject, and price. There are many resources on this page that are also free.
Scholastic is a great place to find teacher resources (teacher and student books, lesson plans, classroom activities, classroom resources, and educational products). Students are also able to purchase books.
Google is a huge resource. It is a search engine that can provide information on anything that you may be searching for. You can look up videos, search images, check the news, search maps worldwide, and get information on any topic that you can think of. It is also extremely easy for the students to navigate.