Jaylene studied shadows by doing this little shadow experiment.
Thick white paper
Tape the balloon holder to the middle of the white paper. Squish the end of the straw a bit and stick it in. Then place the paper outside (weigh it down if necessary) and copy the shadows at various times during the day (without moving the paper). If you can’t leave the paper out, be sure to remember exactly where you placed it. You can extend this over several days. Make sure to note the time and/or date when you measure it.