Perhaps you should try some spelling variations:
"small school surveys." » "small school survey.", "small schools surveys."
"math skills surveys." » "math skills survey.", "math soil surveys.", "motor skills surveys."
"math firm surveys." » "math firm survey.", "data firm surveys.", "rate firm surveys.", "matched firm surveys."
"math hiv surveys." » "math life surveys.", "math soil surveys."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("math skills surveys.") or ((((("math hiv surveys.") or ((("math site surveys.") OR ("math firm surveys."))))) or ("small school surveys."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("math skills surveys.") OR ((((("math hiv surveys.") OR ((("math site surveys.") OR ("math firm surveys."))))) OR ("small school surveys.")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"math skills surveys.\") or (((((\"math hiv surveys.\") or (((\"math site surveys.\") OR (\"math firm surveys.\"))))) or (\"small school surveys.\"))))".
• Removing quotes may allow a broader search: (( math skills surveys. ) or ((((( math hiv surveys. ) or ((( math site surveys. ) OR ( math firm surveys. ))))) or ( small school surveys. )))).
• Adding a wildcard symbol may retrieve word variants: (("math skills surveys.") or ((((("math hiv surveys.") or ((("math site surveys.") OR ("math firm surveys."))))) or ("small school surveys."))))*.