Chanukah science...Candles, air, and a bowl of water

This week the kids explored the effects of using a graduated cylinder to cover a lit candle standing in a bowl filled with water. What happens and why...these were the questions we set out to discover. Some of the results were easy to spot. Others required repeating the experiment multiple times.

Melting Away

This week we investigated what happens to the temperature of ice as it melts. We measured the temperature every minutes for 10 minutes, while checking to see if the water was solid, liquid, or gas.

Initially the temperature was a FREEZING -10° C. Not surprisingly the temperature started to rise, but then something funny happened.  As the temperature approached 0° C, it stopped changing. Yet, the ice was still melting. Clearly heat from the surroundings was being absorbed by the ice, but to look at the temperature, you'd never know it. Then, as soon as all the ice was melted into water, the temperature started to climb once again. 

From this experiment we learned two things: 
1) The freezing point of water is 0° C
2) At this temperature, the energy flowing from the environment into the ice is being used to change the water from a solid to a liquid, resulting in a constant temperature until all the water is in the liquid state.  

We see the same thing happen as substances move between liquid and gas states.

Popcorn Science

This week we did a little popcorn science, the questions being: what happens to the mass and volume of popcorn after you pop it and why does heating kernels make them pop? 

We measured the mass and volume of a sample of kernels and then threw in some oil (30 ml / 23 g to be exact). We put all the popcorn into a pot with said oil, turned on the stove, waited, and then POP! We took out the popcorn, weighed it, measured the volume, and here's what the kids concluded: The kids predicted the volume would increase and so it did...practically by a factor of 10. The mass, on the other hand decreased a tiny bit. 

As for why the heat makes it pop...turns out there's a tiny bit of water inside each kernel, which when heated expands and exerts enough pressure to burst the kernel open. As each kernel "explodes", its volume increases while at the same time allowing a small amount of water to escape, accounting for the slight decrease in mass.

Measuring the Volume of Stuff That's Shaped Kinda Weird

We learned a new use for graduated cylinders. Turns out they're not just good for measuring the volume of liquids, but used cleverly can help us measure the volume of objects that are shaped kinda weird. When it comes to simple shapes, like a block, you can use a ruler to measure the different dimensions, but with something like a screw or a paper clip, how do you figure out EXACTLY how much space it takes up? Here's a clue: What happens to the water level when you get into the bath and why?

Slime flies when you're having fun

How to make slime that has just the right consistency - neither too sticky, nor too watery?
It's all in the measuring...

Over the past few weeks, we've learned how to measure liquid volumes using a graduated cylinder, how to measure mass with the digital scale, and how to mix different colored water to make a rainbow of possibilities. This week we put these skills to good use making the ultimate SLIME! 

Can you weigh and chew gum at the same time?

Did you ever wonder what happens to the mass of gum as you chew it?

To investigate this question we used a scale to measure the mass of the gum at one minute intervals. Now, I know what you're thinking...how does one chew gum and weigh it multiple times without being REALLY gross?!  Bubble gum wrappers make great weighing paper, so we just made sure to measure the mass of the gum in its wrapper before and after chewing it.  Still a little gross, but nothing our scientists couldn't handle.

After graphing the data we observed that the mass decreased, and surprisingly, it didn't happen at a constant rate. Most of the sugar was lost in the first 2 minutes, and after that there was relatively little change. After analyzing our results we wondered if bubble-blowing and talking might affect our results.

Measuring Mass

This week we added the triple-beam-balance to our repertoire of measuring tools. First we discussed the difference between volume and mass, and then we worked in pairs guessing and weighing different objects. Finally we checked ourselves and the triple beam balances using a digital scale. We noticed that a) we measured pretty consistently, and that b) our triple beam balance was only off by about a toothpick. Not that big a deal, unless of course, you're measuring toothpicks!

So what do you think weighs more...a pound of gold or a pound of feathers?

Always chasing rainbows

This week during science the kids got A LOT of practice using a graduated cylinder. Each team had to follow very specific directions for adding and subtracting precise amounts of red, blue, and yellow water to produce a beautiful rainbow of colors. Afterwords we discussed possible sources of error including: spilling, not following directions, measuring incorrectly, and in this case, the starter blue water being too dilute, accounting for the strange greenish color all the groups got instead of purple.

Just for fun, estimate the volume of...

* a mouthful of water
* cup of apple juice
* a kiddush cup
* water used in your average bath

Then check yourself with a measuring cup. (This experiment was conceived during dinner one night when one of my kids INSISTED that the other one got more juice...)