This is the physics of sound you can hear: the more air in the bottle, the lower the note. Tuning the bottles by ear is great listening practice, and getting a clear note takes a little persistence.
The steps are in the app
Step-by-step instructions, tips and an easier and a harder version are waiting in the Hopsa app – along with 300 more ideas matched to your kids’ ages.
Coming soon to the App Store and Google Play
