About major seconds in major keys

Today I'm going to teach you about the interval of the major second in major key. The interval of the major second is simply the distance from C to D. It's like a whole tone. It can be measured it two ways - in scale degrees and in steps.

In scale degrees - from C to D there are two scale degrees.
In steps - it's a whole tone.

Let's first figure out how many major seconds there are in C major scale.

From the 1st scale degree (C-D) - it's a major second.
From the 2nd scale degree (D-E) - it's a major second.
From the 3rd scale degree (E-F) - it's a minor second.
From the 4th scale degree (F-G) - it's a major second.
From the 5th scale degree (G-A) - it's a major second.
From the 6th scale degree (A-B) - it's a major second.
From the 7th scale degree (B-C) - it's a minor second.

So you see that there are 5 different major seconds in every major key (from the 1st, 2nd, 4th, 5th, and 6th scale degrees). Since I showed you how to construct them, now we can talk about how you can resolve these dissonant intervals.