Science Buddies: "Ask an Expert"

My son's second grade teacher asked me on Thursday if I could help with their class project. I said, "sure" then she told me the due date..2-06-09! Yikes!

Anyway, my son and I looked through a great book with a lot of experiments and we found one that I thought would be fun for a whole class to do. It involves taking two balloons, blowing them up to the same size and then putting one in the freezer and the other in a box. We would cut a whole in the box and insert a hairdryer and warm up the air inside. Hopefully the cold ballon gets smaller and the warm one gets bigger. I thought that the 7 year olds would enjoy predicting what was going to happen and also running the hairdryer!

When I was explaining the project to my 7 year old, and I told him how cold air effects things, he said, kind of like how the quartet with Yo Yo Ma (have to love the name!) that played at Obama's inauguration couldn't play cause it was so cold?

Then I thought now that is an interesting idea for a project. I know that the cold air could make the instruments out of tune, but how can a class of 7 year olds prove that?

Also, could it be a different project idea to show the children a tape of the preformance, and then tell them that the muscians were not really playing. And then, ask them what they think about that and do they think that it is right that the people in the audience thought that they were listening to the musicians play, but they were really listening to a recording. We could graph the students opinions (do they think that this was "right" to pretend to play) Then, we could explain why the musicians couldn't play, maybe do a demonstration with an out of tune instrument and then get the kids opinions again and graph their opinions after they have all of the facts?

I was so excited to find this forum and am now excited about the project. I think that we could make a really exciting display with pictures of the instruments and preformers and Obama. I also thought that it would be good to have some of the stronger students do some research at home and answer the following questions which could be compiled in the report:

• What are the names of the musicians
  What was the name of the song that they performed
  What instruments did they play
  What was the temperature that day
  etc

So, in summary, if our project question is, "How does cold weather effect musical instruments." Does anyone have an idea for an experiment? Also, can I relate the balloons, or does that not really have anything to do with it. If our project question is, "Was it fair for the quartet to pretend to play at the Inauguration" Is that really a science fair question? Thanks so much!

- an overwhelmed 2nd grade room mom!

Hello and welcome to the forum!

With regards to the balloon experiment, I have a couple of suggestions. First, how would you show that the cold balloon was smaller than the warm one? They may not be much different (unless either the freezer or the hair dryer pop the balloon!) This would be a fun experiment to demonstrate volume to the kids. (This might be especially fun in that developmentally, kids at this age may not be able to guess volumes by size easily, as Piaget found out.)

Here's my idea. You could take a bucket of room temperature water just full enough to cover the balloon. Mark the water level, then put the balloon in the water and mark how far the water rises. This corresponds to the volume of air in the balloon. Put ice in the water, and get the level back to the first mark on the bucket. Insert the same balloon and wait for it to cool down. The water level should drop as it cools, and the final level should be below the mark for the room temperature balloon. Next repeat with hot water (at the same level as the original mark). The level should rise as the water warms! Sounds like a fun experiment!

With regards to the asking people what they think experiment, that's a behavioral science experiment - those experts are on a different forum

For the musical instrument experiment, it might be fun, but I doubt anyone with a nice instrument would let you subject it to temperature extremes

You could, however, combine it with making a simple stringed instrument with the kids. That would also be fun, and there should be examples on the internet. Have fun and feel free to ask us any other questions!

Keith

I could be wrong, but I don't think second-graders are going to have much of a sense of right and wrong when it comes to performers 'lip-synching' to previous recordings--they're just too young and unless their parents specifically said something about it, I doubt they'll have an opinion either way. It doesn't mean you can't tell the story and still have the visuals and ask students to research it and everything; I just don't think asking students to put a value judgement on it is going to teach them anything about the scientific process.

I do like the balloon idea, and I think you can do something with instruments, especially if you live somewhere where it's cold outside. Here are a couple of ideas:

Find someone in the area who plays a stringed instrument and ask if they would be willing to play a quick song in-tune in the classroom and then take the instrument outside and play another song without re-tuning. While no one is going to let the students play their nice instruments, they'll probably be willing to play them themselves as long as it's not too cold outside. Actually, in this case you might ask students to choose which sounds better, since in this case there is a 'right' answer (one in-tune, one out-of-tune).

Have them make a stringed instrument like kgudger suggested. One simple way to do this would be to have the students string rubber bands between nails on wood. They can pluck them, figure out the sound, then put them in the freezer and try again in an hour or so. If they have computers, you could download a free sound analysis program and record both sounds so you can compare their frequencies.

hey y'all-

Thanks so much for your replies to my plea for help! I was thinking that I could measure the circumference of the balloons with a string before and after. Tate (my 2nd grade) are going to try this experiment today after school and see how much the temperature really effects the balloons.

I really admire the experts on this forum for taking their time to answer all questions! you are providing a valuable service, and hopefully sparking alot of much needed interest in the sciences!

Just think, you may be aiding the next great Einstein!!

If you don't mind doing a "wet" project, you might try a displacement method of measuring volume. Hot water for the hot balloon and ice water for the cold balloon. The Reynolds equation is PV=nRT. For balloons, PV are releated by elasticity properties of the balloon which change with history. From 0 degrees C (ice water bath) to 30 degrees C (about 85 F) you are only going to get about a 10% change in PV because T is in degrees Kelvin (which makes it 273 K to 303 K, 30 degrees out of 300 degrees). This means you don't have much room to spill water that isn't measured. Methods that just measure the circumference will be even more sensitive to experimental and measurement error.