"Impedance can be found by measuring the voltage across the speaker motor and calculating the current through the circuit."

X = 2πFL for inductive circuits. I assume I find resonance (and from this paper I understand that resonance is where inductive reactance and capacitive reactance are equal), then plug the values into that formula. But I don't know the inductance. Furthermore, from I=E/Z, we can derive Z=E/I. Fine. The signal generator I ordered puts out 1.2V RMS. I don't know the current it puts out.

I'm to put a 10 ohm resistor in series with the speaker coil. Am I to break the circuit at Zmax and Zmin and measure current draw with a milliameter?

Do I then measure voltage drop across the coil once I reconnect the circuit?

"This reactive circuit (inductance and resistance) forms a voltage divider, so you can use Ohms law and reactive circuit formulas to determine the impedance of the motor."

We put the resistor in series with the coil. I don't understand how this is a voltage divider. Where are we dropping the divider to ground?

These questions certainly must seem naive to you, but again, I'm a hobbyist who just wants to build a speaker.