Searching for an exact phrase can narrow a search considerably. Quotations around a keyword or phrase will help. If you are interested in the impact of computers on writing instruction, for instance, you could search for the exact phrases, "computers and writing instruction" or "computer-assisted writing instruction."
A 2006 Google search produced some astronomical numerical results using these phrases. Enclosing them in quotation marks removed from the search all records other than those containing the exact phrase, resulting in a significant reduction.
Simple Search: computers and writing instruction
Result: 101,000,000 records
Search in Quotations: "computers and writing instruction"
Result: 131 records
Simple Search: computer assisted writing instruction
Result: 9,360,000 records
Search in Quotations: "computer assisted writing instruction"
Result: 608 records