In this lesson, search engines are introduced in more detail. Emphasis is placed on the fact that these are collections rather than selections and that there are no humans involved in the collection process. Students explore some search engines to see the differences in results.
After this lesson, students will
- understand what a search engine is.
- understand the key differences between a search engine and human-created directories.
- know that when using a search engine, it is more desirable to have fewer hits.
Hard copy of this lesson plan PowerPoint slides Now You Try It #3 (PDF) Now You Try It #3 (Word)
- Collect examples of books which would come up in a library "search engine" based on the word "explorer" (e.g. topical books, books with the word in the title, books with the word somewhere in the text)
- Review lesson 3 PowerPoint presentation for content prior to lesson. (Note that the presentation may need to be adapted for your specific situation before use.)
- Complete sample searches prior to lesson so you can choose the best examples which relate closely to current class topics and/or student interest.
- Prepare copies of the Now You Try It! worksheet #3
- Review Lesson #2: Three steps for Internet research
- Review subscription databases and subject directories
What is a Search Engine and How Does it Work?
- Robots ("Spiders, Webcrawlers")
- No more human selection
- Collection rather than selection—everything on the Web is included in a search
- Show Google and show number of sites indexed (at bottom of front page) and number of hits for a key word (e.g. "Columbus").
- Getting results with a search engine vs. subject directory
- Search engine gives many irrelevant hits
- Subject directory gives fewer but more focused results
- Let students check comparison of hits between a directory and a search engine for a specific topic
- Emphasize that fewer is better!
- Specific examples of search results
- any current classroom topic
- What if the librarian were a search engine crawler? (Show examples of books that have irrelevant content but include the search term.)
- Student exploration time to try searches on current class topics, personal research topics, or both, using both subject directories and search engines.
Now You Try It!
- Student partners work together to search for their explorer by name in each of the following:
- Subscription database
- Subject directory
- Record the number of hits for each search on the Now You Try It! worksheet.
- Write down which search method would be the best choice for correcting the wrong info at AAE and why.
Summary & Preview of Next Lesson
- Review and emphasize that search engines are completely programmed—no human judgement or evaluation is done for you.
- Next lesson will focus on how to navigate on the Web and evaluate web sites.