Are you passing the hours during a snow day, or the latest winter storm, or just having a day that’s too cold to venture outside? Then this hourglass project is for you! It will make watching the passing hours into a fantastically cool experiment.
To start, you need two identical bottles (we used empty water bottles that were 1 liter).
Hot glue the caps together, pressing for a tight seal.
Next add a piece of duct tape, to make a water-tight seal.
Mark two dots where you will insert straws, then (grown-up step!) drill through the holes.
Cut straws into pieces that are 2-inches long. Insert one straw 1/3 of the way into one of the holes. Insert the other straw 1/3 of the way in the other direction.
Fill your first bottle with vegetable oil. Definitely use the cheap stuff here, folks, since the bottle needs to be filled completely. We used a funnel to avoid any mess.
Fill the second bottle with water. We added blue food coloring for visual effect.
Now screw one half of the bottle cap onto the bottle with oil. Quickly and carefully, flip over and screw onto the bottle with water. Immediately you’ll get a big bubbling result as the two liquids start to mix.
After a few minutes, the bubbles will settle down and you can really see what’s happening. Because the oil is less dense than water, it will bubble up, bit by bit through the straw, at the same time that the water bubbles down.
First, we were simply in awe of how cool this looked.
Then we decided to get more scientific: Had we really created an hourglass? We timed it and discovered it took 45 minutes on the dot before we had one completely blue bottle, and one completely oil bottle.
And then there’s the fact that this is simply mesmerizing to watch. Seriously, I could have meditated in front of these bubbles.
And Travis’s glee made it apparent he felt the same.
Although not necessary, you can decorate your bottles, too. Since the blue and yellow effect reminded us of sand and water, we added a little octopus and his cave…
…and these fishy friends.
What a way to watch the hours pass!