Too many results? Or, not enough? Not the right type of resource? Click the "Modify Search" link to open "Advanced Search" options--the screenshots below may provide additional guidance.
The AND will narrow your results because they will have to include BOTH search terms.
The OR will expand your results because they will just have to include EITHER of your search terms. Use this for synonyms and similar keywords.
If you've limited by "Location", you should not need to also limit by "Material Type". Common uses of limiting by "Material Type" are to only return resources that are books or videos.
Limiting by "Year" will limit your results to those published within the dates you select. The most common use of this limiter is to enter an "After" date; this is helpful because some assignments will require resources only published within the last 3-5 years.