It should be obvious, I think, but when writing virtually any kind of college-level paper, and particularly a technical paper such as a report of an experiment - avoid colloquialisms.
There's one in particular that shows up again and again in student papers, and that's "look at" or "looked at". Here's an example:
In another study, Kahn and Wansink (2004) looked at how variety of food influences consumption in children and adults.Normally I'm in favor of using plain language rather than going for the $20 word, but in this case the plain language is imprecise and does a disservice to the scientists you are citing. The proper way to write this sentence is:
In another study, Kahn and Wansink (2004) tested the effect of food variety on food consumption in children and adults.I've cleaned up the second half of the sentence here, but the important change is replacing "looked at" with tested. Other replacements for "looked at" include examined or studied. Although one definition of examined is pretty close to "looked at", examined at least implies looking at something closely. It implies that some form of analysis is taking place, a process that is not implied by the verb phrase "look at".
Even better are studied or tested. These verbs correctly imply that the scientists are setting up special conditions that allow inferences to be made about how variables influence one another. Any one can "look at" something, but it takes special care to examine something, and it takes a very particular arrangement to study something or to test an idea.
And in this case, the more precise word also provided economy. "Look at" is a two-word phrase and requires an ugly and cognitively demanding preposition. Test, examine, and study are clean, precise, single-word active verbs that do the job better.
It is true that one should write as naturally as possible, reduce complexity in long sentences, and avoid unnecessary jargon. But in following such advice, one must also avoid colloquialisms and choose the most precise word or phrase.
