Assignment criteria is what you'll be assessed on. Every rubric, verbal instruction, prompt, or other piece of information that describes what's required for your assignment is your criteria. Your criteria also helps guide how to develop a topic, and plan a search.
EX: "Find 3 recent (last 5 years) peer-reviewed articles on a topic related to college students. Summarize the articles, and provide a references page in APA Citation."
This already gives you several pieces of information about how to search for information.
You can combine AND, OR, and NOT to build very complex searches. Group each concept in parentheses.
Let's say that we only want to look at topics for college testing, not K-12. We need to include college results and exclude earlier grades:
(test or assessment or examination) AND (college or university) NOT (elementary or "middle school" or "high school").
The Search Strategy Builder is a tool designed to teach you how to create a search string using Boolean logic. While it is not a database and is not designed to input a search, you should be able to cut and paste the results into most databases' search boxes.