When writing intervals on the staff, it is common to confuse intervals with the same number of semitones. For example, during practice, one accidentally writes C to F # (increasing fourth intervals) as C to Gb (decreasing fifth intervals). Although these two intervals sound the same, one is a fourth and the other is a fifth.

Now, there is a simple three-step method that can reduce the probability of such errors. Let us write a small third interval in C key

First, write a third interval on the staff

Next, calculate the number of upper half tones on the keyboard. Since the major third interval is 4 half tones, the minor third interval will be 3 half tones.

Finally, compare the number of upper half notes between the piano keyboard and the staff, and add a rising and falling sign. C-Eb is a small third interval.

Next example, try writing a major sixth interval starting from F #.

First, write a sixth interval on the pentagram

Next, calculate the half tones on the keyboard, where a major sixth interval is 9 half tones.

Finally, it is necessary to calculate the rise and fall sign, where F # - D # is a major sixth interval.

In the final example, try writing a minus fifth interval starting from B.

Firstly, write the fifth interval on the staff.

Next, calculate the half tones on the keyboard, because a pure fifth interval is 7 half tones, then a minus fifth interval is 6 half tones, and B to F are a minus fifth interval.

Use the table below to refer to the process of writing intervals.