I try very hard to be one of those down-to-earth folks. I don’t like to wear my degree on my sleeve; I can discuss diaper rash or the latest TV show with the best of ‘em. I hate when people drop ten dollar words to show off their pedigree. However, occasionally I do slip up and assume that someone knows exactly what I’m talking about. For example, last week I was showing a friend how to use a sewing machine. After my five minute discourse on how to make a bobbin, she sheepishly asked, “What’s a bobbin?” Oops…teacher FAIL!
In my last post, aimed at my peer group (parents), I mentioned teaching your children to love science for a lifetime. I casually used the example of demonstrating a meniscus to your kids. A dear friend, whom herself is well-versed in science, admitted she didn’t know what a meniscus was and had to look it up. Oops again. My mistake. I’ve used the concept for so long (since I was a sophomore in high school, which was…ahem, cough cough…a couple years back) that it is as second nature as riding a bike. So, here goes:
Meniscus [mi’ nisk?s]: the curved surface (produced by the surface tension) of a liquid standing in a tube; concave if the sides are wet, convex if not.
Ok, so in everyday-speak, what does that mean? Well, I think of it a lot like my bra…where there is support (ie the glass sides of a graduated cylinder or measuring cup), the liquid holds “up” (surface tension). Where there is no support (in the middle), you have sag. Hee hee. When measuring liquid, the fluid will stick to the sides of the container and “sag” in the middle. (This is very subtle, but does happen) If you look at the liquid height at eye level, you should read the amount as the bottom of the meniscus. In even simpler words, the top of the liquid is observed from the side, it will look like a bowl. The correct measurement is the bottom of the “bowl,” not the sides.
Hope that helps.
PS: Ok, so now that you know the nitty-gritty on liquid measurements and that’s enlightening, what about that science fair project that’s due next week? Go to 24 Hour Science Projects to help you on your way!!