Homemade compass

We decided to build our own compass to help orient us for our stargazing. We magnetized a paperclip using our dangerously powerful- magnet (rubbing the paperclip across the magnet many times). We filled a container with water and put our now magnetized paperclip on a piece of cork in the water. The paperclip and cork slowly rotated until it was oriented north-south. We spun the cork around multiple times and it kept re-orienting itself. Pretty cool to see this invisible force at work (although next time I'll use a round piece of cork so it doesn't get stuck on the edge of the container without being able to turn). Jr. Scientist A liked the experiment, but I have a sense that the underlying concept of the earth having a magnetic field was a little too advanced.

Why does yeast make dough rise

Jr. scientist A often asks why we add different ingredients when we cook and one of the common ingredients we use (since we make a lot of pizzas) is yeast. I decided a while back to try to give a better answer than my standard, "yeast makes dough get bigger" response. I knew that there was carbon dioxide being released that formed little pockets in the dough, thus expanding it, so I thought we could do an experiment where we use yeast to blow up a balloon. Originally I put some yeast and water in a bottle and covered the mouth with a balloon. We checked on our experiment the next morning to find a still deflated balloon. I tabled the experiment for a while and was poking around online and found I was missing a key ingredient - sugar. We re-did the experiment with two bottles. The smaller bottle had yeast and water and the bigger one had yeast, water, and sugar. By the next morning the bottle with sugar had a nicely bulbous balloon sitting on top of it. Thanks to some laziness, we discovered that the bottle without sugar did eventually make enough carbon dioxide to partially inflate the balloon, but it took a few days to happen.

Levitating ball

This is one of those experiments that I've seen in a number of books and kept passing up because it seemed like one of those experiments that looks like they should work but never do. The idea is that you use a hairdryer to "float" a light ball in the air. It works using Bernoulli's principle (the same principle behind airplane flight) - the fast air moving around the ball creates an area of low pressure, effectively acting to hold the ball in a tunnel. We were flipping through one of our books and Jr. scientist A found that experiment and asked to do it. I reluctantly got out the hairdryer, pointed it up and placed it on cool air, and gently placed the ball in the air stream. I was more than a little surprised to see the ball just float there on a cushion of air. Then Jr. scientist E did the next logical experiment - she nudged the ball. It moved a little and then moved back on its own to the center of the air stream like it was attached to a spring. That really got her excited. We all had a lot of fun with this experiment.

New telescope toys

We got some new equipment for the lab telescope - a moon filter to increase clarity and a camera mount to help us take pictures. We're still learning to use the camera mount, but jr. scientist A is having fun taking pictures and movies of the moon.

Expectations

Although we've had our fair share of "dud" experiments, some experiments, albeit technically successful, don't land with the jr. scientists. It seems that there is what I can only refer to as an expectation gap. The experiments that have the biggest wow factor tend to be those that defy expectations. I suspect this is why bubbles are so fascinating to young children, and for adults it takes the bubble-suspended-in-space experiment to make bubbles cool. Likewise, the realm of possible is considerably smaller for adults, and some things that are expectation-defying for adults are just normal occurrences for kids. The other night Jr. Scientist A, myself, friend-of-the-lab David, and visiting Jr. Scientist S went to a mars rover landing party. As the rover landed on mars and sent back the first photos, the adults made a valiant effort to convince the kids that this was a big deal and really cool. The excitement of the moment was somewhat lost on the jr. scientists, and I suspect that the muted reaction was related to Jr. Scientist A's question to me earlier that day asking if we could go to mars the next day. I guess when making a day trip to mars is part of your normal expectations, seeing a grainy snapshot from the red planet just isn't that exciting.

Exploring the lunar surface

Since jr scientist A has quite an interest in outer space, we decided to investigate why the moon looks like it does. I ran across this experiment in Pop Bottle Science (yes, I know, this has nothing to do with pop bottles). We looked at some pictures of the moon with all its craters and I asked jr. scientist A where he thought all those bumps came from. He didn't have any idea so we got out a container and some flour and made a mock lunar surface. Then I rolled a piece of play-dough into a little ball and threw it into the flour resulting in a mock crater in our mock lunar surface. Jr. scientist A had lots of fun making craters and it seemed to really make sense to him. It was a great way to explain an otherwise difficult to conceptualize idea (I wish I could take credit for coming up with the experiment!)

Electromagnets

After previous unsuccessful attempts to make an electromagnet (and my clear deficiency in electrical experiments), we turned to my first science teacher, Dr. A, for a little help. After finding the right type of wire (who knew there's a lightly insulated wire labeled specifically for making electromagnets - well I didn't, but thankfully Dr. A did!), we quickly had our electromagnet up and running, complete with a light switch that turned the magnet on and off. Jr. Scientist A had fun flipping the switch on, picking up metal objects like paperclips and silverware, and then flipping the switch off and watching them drop. Some paperclips did get temporarily magnetized, making the dropping effect a little less dramatic and the concept a little less clear, but it was still quite a success.