Minor Scales - Natural, Harmonic, and Melodic

https://www.youtube.com/watch?v=Q7WqKpD7w4Q

How to Master the Circle of Fifths and Your Key Signatures in One Easy Lesson

https://www.youtube.com/watch?v=1swhMTSFayI

Music Theory made STUPIDLY easy - PART 1 - Notes, Chords and Melodies

https://www.youtube.com/watch?v=rZr5k1_9Dds

Music Theory Net

Music Theory Net has some good test for theory learners:


To test your Key Signature Identification:

https://www.musictheory.net/exercises/keysig


To test your major scale:

https://www.musictheory.net/lessons/21

Play With Your Music Theory: Advanced White Key Wizardry

https://www.youtube.com/watch?v=DMbbj6y_gFU

Learn Piano Scales: Major, Natural, Harmonic, Melodic Minor & Chromatic Scales

https://www.youtube.com/watch?v=aClctmxVMDU