Herbal Marshmallows

17 10 2013

Come read about our homeschooling adventures into herbalism here.


Science: How Submarines Float

31 07 2010

For our science lab, we began by reading about tornado chasers and severe weather, and learned about the history of meteorology. We learned about how weather scientists learn about weather in the past, from tree rings, old diaries, and Antarctic ice, which is filled with ancient air bubbles. We learned some weather folklore sayings, and guessed whether they had any basis in science or not.  Then we moved on to learn about science in the water.

We learned about ocean engineers, who study the movements of fish to make better submarines. That led us to our lab, to learn how submarines work by experimenting with pop bottles.

This is what happens to a bottle filled to the brim with cold water in a basin of cold water. It sinks to the bottom.

But, you can pump some water out of your submarine by blowing in air:

Then it floats just below the surface of the water. Up periscope! (The same thing happens when you fill the bottle with hot water, incidentally.)

But an empty bottle cannot be made to sink even part of the way. No matter how much you push on it:

Here are Floppy’s lab notes, which ran for two pages:

Science: How Warm and Cold Air Behave

23 05 2010

In science, we’re still studying air (in our Childcraft science text). Today, we read about how  powerful air is (demonstration: blow up a balloon and let it go. See? Powerful!) and how people use it (exhaust fans, clothes dryers, wind turbines, food preservation, how helicopters fly, etc.). We also learned about storm fronts, and how air masses move around the planet, and what happens when warm and cold fronts collide. Finally we did an experiment to illustrate the differences in how warm and cold air behave.

To do the experiment, you’ll need four identical bottles (we used brown glass beer bottles courtesy our brewer friend Charles Bristle), four identical balloons (we used green water balloons), equal amounts of very hot water, room temperature water, and ice water, and three identical bowls big enough to hold your water plus a bottle standing upright.

The experiment is simple. You stretch a balloon to fit over the neck of each bottle. You pour one temperature of water into each bowl. Then, all at once, you stand each balloon-covered bottle upright in a bowl of water, leaving one balloon-covered bottle outside a water bath as a control. What happens next is quite impressive:

The bottle in the middle is in room temperature water, and it looks the same as the bottle that was not in the water at all, and also the same as all the bottles looked before going into their baths — the balloon is taught and upright, but not expanded. The bottle on the right is sitting in near-boiling water, and it immediately puffed up and expanded. The bottle on the left is, as you can see, in ice water, and as the air sunk and shrunk, the air was drawn out of the balloon and it collapsed. This all happened immediately and was dramatic and cool to watch.

Here’s how Floppy recorded it in his lab notebook:

The text reads: “5-23-10. The boiling hot water’s balloon puffed up so fast and the 2nd one did it slower and the third one got smaller. This happened because it’s hot air and hot air expands. It [the cold air] went into the bottom of the bottle and got smaller. And the air in the controls didn’t do anything.”

Science: Atmospheric Pressure

6 03 2010

We’re doing a science unit about air from Science, Science, Everywhere. We read about atmospheric pressure and learned a number of interesting facts. Did you know that there is about 2000 pounds of air pressing down on you right now? I didn’t. We read about what air is made of, how much earth’s atmosphere weighs (5.75 quadrillion tons!), how thick it is, and how temperature, humidity, and land elevation affect air pressure. We learned about pressure systems and their role in creating weather, what meteorology is, how both mercury and aneroid barometers work, and what different barometer readings mean. Then, we made a barometer of our own. Here it is:

Today’s reading is 7 cm. No idea whether that is high or low, but I guess we’ll figure it out as we take readings over time. Note the notepad for daily pressure readings. Also, that little dimple on the barometer top? Childcraft specified a latex balloon as the right piece of equipment to make the top of the barometer. But we didn’t have any balloons. After some pondering, mama realized she had a good substitute available. Ahem.