Last fall I wrote 10 Search Tools and Tactics Teachers and Students Need to Know. The first thing on that list was to teach students to stop Googling "what" and "why" questions. In other words, teach students to use better search terms. A good resource that can help students understand web search strategies is Common Craft's Web Search Strategies in Plain English.
The video can be viewed online. If you would like a copy to download or embed into your blog like I have done above you will need to have a Common Craft subscription.
Disclosure: I do have an in-kind relationship with Common Craft.