I waited for a few minutes at the counter while the grocery store employee was finishing up some things in the back.
When she approached the counter and asked how she could help, I started to tell her what I wanted.
"I need about two cups of shrimp for -"
"We don't sell shrimp by the cup. We sell it by the pound," she said, looking at me as if I was the most simple-minded person in the store.
"Yes, I know, but I was wondering, since you measure this all the time, if you could estimate how many ounces or pounds it would take to make two cups."
"We don't sell shrimp by the cup," she said, clearly frustrated at me.
I decided not to press the issue and asked for about a pound of shrimp.
"Could I see that when you're done? I can eyeball it to see if it's the right amount."
I later related this story to my children. My son wanted to know why the store didn't teach its employees to make common-sense conversions. Good question.
Using common sense begins at home. Perhaps parents need to do a better job at encouraging children to use their reasoning skills, even when it comes to simple tasks. We try to do this around the dinner table.
After dinner Saturday, we were each sharing stories from the week. Our son - who loves to stump us - shared a brain teaser from his science magazine.
See if you can figure it out: Move one digit to a new position so that this equation is correct: 62 - 63 = 1. (Moving the signs is not allowed. The answer is at the end of this column.)
After we discussed that math problem, my husband shared a teaser of his own:
There are three light switches in one room and three light fixtures in another room. How can you determine which switch controls each fixture? You can turn on any of the switches, but you can go into the room with the fixtures only one time. (You cannot see the fixtures from the room where the switches are.)
We thought he was testing us on some high-tech electrical information, so we said that question wasn't fair for us, coming from him. (He's an electrician.)
No, he assured us, the question could be answered just by using common sense.
Do you know the answer?
We couldn't figure it out, so he explained it to us.
Turn on one light. Leave it on for a while and then turn it off. Then flip a second switch. Go in the room. The light bulb that is off but hot to the touch is controlled by the first switch. The light bulb that is on is controlled by the second switch. The light bulb that is off and cool is controlled by the third switch.
Oh, that was almost too clever for dinnertime conversation.
Brain bender answer: Here's the answer to the science magazine question. Move the first six so it is an exponent of the two. Two to the sixth power is 64. 64 - 63 = 1. This problem was featured in the Nov. 14, 2008, edition of Current Science magazine, a publication of Weekly Reader, www.weeklyreader.com.
Lisa Tedrick Prejean writes a weekly column for The Herald-Mail's Family page. Send e-mail to her at firstname.lastname@example.org.