The simple search is just simple: You can search for a string contained in the description, the keywords, or the title of a teaching or learning material. The search is case-insensitive and finds the string inside words.
If you enter several strings separated by spaces, all of the strings must occur in the result. You can exclude a string from the results by prefixing it with a minus sign "-".
The advanced search allows you to specify the facets to search. So you can ask for material of the level "basic" or for material aimed at the target audience "historian".