Hi! Future Ticia 2025 here, I’m going through and streamlining my site and realized I essentially have this post twice. The first time is this post, where I said, “Hi, I did this thing, but I’m so behind, I’ll get it up here later.” Then I came in later, wrote an entire second post titled it, “The actual Water and Air pressure science lesson.” Fast forward 13 years, and I realized I really don’t want two posts saying the same thing. Then in a bit of brilliance I accidentally deleted all of the text from this one a little too early, but don’t worry, it most told you the story I just gave you with a lot more amusing side stories from 13 years ago. Now I’m going to copy over the science lessons we did all those years ago, which really was a great physics lesson for some first graders, that was a pretty amazing lesson that I’m having fun reliving as my kids are out of the house.
Here’s past Ticia 2012:
So, obviously I never got that post fixed last week. First, I was wrongly reported as having malware, so I had to work on that. Then I had two very hyper little girls who wanted lots of attention. LOTS of it.
THE QUESTION: Why does the water stay in the straw when you put your finger on it?
THEORIES: There’s something stopping it from getting out. We don’t know what.
First, I had them figure out what I was doing differently from them that kept the water in the straw. They tried several different ways of holding the straw to duplicate my keeping the water in, but didn’t figure it out until I showed them what I did very slowly. Then I heard:
“OH! It’s just like the Thumb pot at Williamsburg!”
Talk about making a Mom proud. They’d drawn the connection between this and the gardening tool they’d seen one time. It also works based on air pressure holding in the water until you take your thumb off the top.
This one is from Farm to Market.
But, they still hadn’t completely figured out what was keeping the water in while my thumb was on the straw, so on to the next part.
Experimenting with water and air pressure formal experiments
Supplies needed for this experiment:straws, plastic cup, index cards
Next, we did the water and air pressure holding the index card on, even though the cup is upside down. A similar principle holds the paper up as holds the water in. I asked leading questions:
What’s under the cup?
If there is no liquid in the cup, what is still in the cup?
After a while, they realized there was air in the cup, and there was air pushing on the paper and air pushing on the water in the straw.
See, if I put my thumb on top of the straw, there is no place for the air to move into where the water is; it creates a vacuum, and the water cannot move out. The same theory works with the cup and the water. If the water is to the top of the cup, there is nowhere for the paper to go because the air pushes it up while the water is pushing it down. Of course, eventually the water soaks through and the paper falls, but for a short time it’s “Amazing Mommy!”
So, that was my quick science experiment we had because I was trying to cool down my son’s tea.
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