DGB 1: Search Engines
Search engines help users find information on the World Wide Web. To use them effectively, students need to understand the difference between a browser and a search engine and know, in simple terms, how web pages are discovered, indexed and ranked.
Curriculum reference
[Bearbeiten]| Area | Classification |
|---|---|
| Competence area | Information |
| Focus | Search engines and their basic functioning |
| Competence | Use search engines purposefully and explain their basic functioning in simplified form. |
Learning objectives
[Bearbeiten]Students can:
- distinguish a web browser from a search engine;
- explain the basic ideas of crawling, indexing and ranking;
- formulate suitable search terms;
- read titles, domains and snippets in search results;
- recognise advertising or sponsored results where they are labelled;
- explain why a highly ranked result is not automatically the most reliable result;
- compare several search results before selecting a source.
Learning content
[Bearbeiten]Browser and search engine
[Bearbeiten]A browser is a program used to open and display websites. A search engine is an online service that helps users find web pages. A search engine is usually accessed through a browser, but the two are not the same thing.
Crawling
[Bearbeiten]Search engines use automated programs, often called crawlers, to discover publicly accessible web pages and follow links. They do not necessarily find every page on the internet, and changes may take time to appear.
Search index
[Bearbeiten]Information about discovered pages is processed and stored in a large search index. The index allows a search engine to respond much faster than if it had to search the entire web from scratch for every query.
Search query and ranking
[Bearbeiten]The words entered by a user form a search query. The search engine finds matching entries in its index and orders them. This order is called ranking.
Many factors can influence ranking, including relevance to the query, freshness, technical quality, links, language or location. The exact weighting differs between search engines and can change. A result near the top is therefore not automatically the “truest” or best result.
Reading a results page
[Bearbeiten]A result usually contains a title, an address or domain and a short text preview. Some results may be marked as advertising. Students should read these elements before opening a page and should not choose a result only because of its position.
Better search terms
[Bearbeiten]Precise keywords generally produce more useful results than vague or very long questions. Search terms can be changed and refined after the first results have been examined.
Classroom activities
[Bearbeiten]Explain crawler, index and ranking
[Bearbeiten]Task: Create a simple diagram showing how a web page can be discovered by a crawler, stored in an index and later appear in a ranked result list.
Browser or search engine?
[Bearbeiten]Task: Classify examples as browsers or search engines and explain the difference in one sentence.
Improve a search query
[Bearbeiten]Task: Start with a broad search term, inspect the results and refine the query so that it better matches a given school question.
Compare a results list
[Bearbeiten]Several results are shown for the same school question.
Task: Compare title, domain, snippet and any advertising label. Explain which result you would check first.
Expected outcome: A conscious first selection instead of relying only on rank.
Self-check
[Bearbeiten]- I can distinguish a browser from a search engine.
- I can explain crawling and a search index.
- I know what ranking means.
- I consciously read titles, domains and snippets in a results list.
- I can improve search terms and compare several results.