dipsticking
n.—Gloss: taking random samples or randomly choosing people to question. «One recent morning, Ms. Cascio asked several students in succession to explain the logic of their answer to the same question—and, “Uh, yeah, I agree with Yasamin and Josh” just wouldn’t do. “It’s called dipsticking,” Ms. Cascio said. “It’s really important to make sure the kids are picking this information up, and so I ask, Is this clear to you? Do you really understand it? and I won’t go on until I get a positive, satisfying answer.”» —“In Science Classrooms, a Blast of Fresh O2” by Natalie Angier New York Times Oct. 30, 2007. (source: Double-Tongued Dictionary)
Further reading
In 1916, a small-town newspaper in Pennsylvania printed a fanciful item about a local gathering with a guest list that included, among others, Miss Ella Vader, Mr. Ray Zor, and other punny names. This is part of a complete episode. Transcript of...
There are word nerds, and then there’s the woman who set up a folding chair on sidewalks throughout the country, cheerfully dispensing tips about grammar. She recounts her adventures in a new book. And the story of the brilliant pioneer of...
I have heard the term used commonly within demeaning phrases. The person is only as smart as what is directly in front of their face. Does not connect any other background or known information with what is facing them in current time/place.
I do like the small irony of this definition from MW’s Open Dictionary:
“dipstick (other) : A stuipd or dum person”
http://www3.merriam-webster.com/opendictionary/newword_display_recent.php?id=4705