When searching for information, it is important that you continuously stop to evaluate the information and the material you are able to find. Is the search result reasonable? Are the texts you find relevant (does it appear to be on the subject you are interested in)? Here you will get some tips on what you can do depending on if the search result is too big or too small.

Is your search result too big?

Limit the number of hits by adding more search terms, for example a geographic location.
Many search engines and databases offer different filters that you can use to limit your result. You can often choose how old you want the texts to be, or what language you want them to be written in.
Limit the search by using more specific search terms. For example, exchange the term "sustainable development" for the more narrow term "ecological sustainability", or change school to "high school".
Advanced search is an option in many search engines and databases. By choosing where your search terms or subject headings should be searched for you can control the result of your search even further. You can, for example, decide that your search term should be found in the title, the author's name, or the subject heading. By making this sort of field search you have greater control over where in the search result your terms should be found. That means that you will get fewer hits.

Is your search result too small?

Check to see if all your search terms are spelled correctly.
Expand your search by using more general search terms.
Expand your search by using fewer search terms.
Try to see if you will get more results if you search in another search engine or database.
What language did you use? Try translating your search terms to English to see if you get more hits.

Is your search result not relevant?

Try using different search terms. Are there any synonyms that you can use? You can look for English synonyms at, for example, the website: thesaurus.com
Try finding more accurate subject headings. Read up on your subject, ask your teacher, or check how some of your classmates did. A lot of databases offers a thesaurus that can give you tips on what words to use in that specific database.
Try to see if you will get more relevant results if you search in another search engine or database.