How search engines rank results
Computer ScienceFiles, Storage & DatabasesAges 14–15
Use it with your class: students open it from a link or a QR code, with no account needed.
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A small collection of twelve web pages with different titles, URLs, publish dates and trust levels. Students type a query into the search box and see how the engine scores each page: a keyword in the title counts for more than one in the body, then the score is multiplied by the page's trust level. Students can use the "exact phrase" operator, a minus sign to exclude a word, and site: to restrict results, then switch the ranking criterion to compare how the order changes.
Lesson: Searching and evaluating information online: keywords, search operators and source trustworthiness
What it shows
A search engine does not understand a question; it matches keywords and ranks pages by a calculated score. In this model, twelve pages about solar energy each have a title, URL, publish date and trust level. A keyword found in the title earns three points, one found in the body earns one point, and the total relevance is multiplied by the page's trust level. Because the order comes from a formula, the top result is not automatically the most reliable, and changing the ranking rule changes which pages people see first.
How to use
Type a query and click Search, then click a result to see how its score is worked out. Turn on Enable search operators and try Add "exact phrase", the minus sign to exclude a word and the site: button to restrict results. Finally switch Rank by between Relevance × trust, Source trust and Most recently published, and compare how the order of the list changes each time.
Parameters you can change
- Starting query
- Number of results shown 3–10 results
- Enable search operators
- Rank by Relevance × trust, Source trust, Most recently published
Questions to explore
- How do the results change when you put two keywords inside quotation marks instead of typing them separately?
- Which page rises to the top when you rank by Most recently published, and is it also the most trustworthy?
- Why can a page with the keyword in its title still rank below a page that mentions it only in the body?
