Science Buddies: "Ask an Expert"

Hi,
My daughter has chosen to do balloon morphing as her science fair project. She filled latex balloons with helium, measured their circumference at room temp, outside in the cold (for an hour), and in a heated room (for 30min.). The circumference changed only minimally (1cm at most). Any suggestions of why or what the problem is? I know when we buy mylar balloons from the store and take them in areas of varied temps there is a dramatic change. Very frustrated right now. Any suggestions or information would be appreciated.
Thanks.

Hi bel36,

I'm not entirely sure what is wrong, but when I took a look at the experiment, I saw these directions:

Place the thermometer and all three balloons—one at a time, if necessary—in the area where you have chosen to do your cold-temperature testing; such as in the freezer.
Wait approximately 1 hour. If you can only put one balloon in at a time, this step will take 3 hours.
Wait 20 minutes to allow your balloons to come to room temperature.
Place the thermometer and the balloons—one at a time, if necessary—in the area you have chosen to do your hot-temperature testing; such as inside a car on a hot day.
Note: Do not put the balloons in direct sunlight or under a heat lamp because this causes the gas to escape from the balloons and will deflate them due to losing gas. This will not let you determine whether the gas contracted or expanded.
Wait approximately 5–10 minutes, or until you can see obvious changes. If you can only put one balloon in the hot area at a time, this step will take up to 30 minutes.

If you are doing one balloon at a time, make sure you have them in the hot or cold area long enough. It also looked like the chart wanted you to measure in millimeters, so you should be having some change (with a size difference of 10 mm). Do you know how much are the balloons' circumference is supposed to change?

Thanks