Searching for information at university is very different from using school and public libraries. Most school libraries are so small that students don't really need to use the catalogue; they can just browse the shelves. Many public libraries have signs on the shelves to show you where resources are on particular subjects. You usually don't need to search the catalogue unless you want to find an item from another branch. School and public libraries have magazines, such as Popular Science, rather than scholarly journals, such as Nature.
At school and in public libraries, there may have been access to one or two databases containing newspaper and magazine sources. Some schools have access to databases that include journal articles. It is daunting for even the most confident student to arrive at university and be confronted with multi-storey libraries and extensive electronic resources.
Mature-aged students, too, may have only used public libraries and may not have had any experience in searching for electronic information.
You could suggest that students use the checklist on the following page when they start their first assignment.