If you’re planning Earth Science this year (which I am), Exploring Earth could be your textbook. It is the interactive component to a high school textbook published by McDougal Littell. You could buy the textbook to go with it (currently going for under $5 used on Amazon), or use it with a different one. It covers all the standard topics for Earth Science, from the solar system to the oceans. Each chapter has interactive investigation including video and activities. The Earth News section links you to a great website showing all the recent earthquake and volcanic activity on the planet as well as stories about the weather, the ocean and other earth science-related news. I will definitely be using this in our middle school earth science unit this year. For middle or high school and free.