We did one of my favorite introductory problems today in AP Physics 2. It's a series of two problems that lulls them into complacency:
Oh, you're asking how the wavelength will change if the frequency changes? Oh, then the velocity must be constant.
Oh, you're asking how the speed changes when the frequency changes? Oh, then the wavelength must be constant.
One of those reasonings can't work, but they're not used to thinking deeply about how three quantities change. They're not used to justifying why what stays constant stays constant.
This is the big jump for AP Physics 2—sometimes, I think it's the whole point of the ideal gas model & phase diagrams for a gas.Â
Oh. they also fooled me with a 440 Hz tone for the bell, and I let them out two minutes early. I gave them too much knowledge.