A triad is constructed of the first, third and fifth notes of the major scale
A major
1. Understand the Theory
A key signature is the sharp signs next to the clef. In this case we have F sharp, C sharp and G sharp. If you need help here please see the key signatures blog.
The tonic triad is the 1st , 3rd and 5th note of the scale.
When there is no key signature this triad requires an sharp sign in front of the C to make it a C sharp.
It does not need a F sharp or a G sharp as there is no F or C in the triad to raise by a semitone.
 |  |
2. Watch the Reel
3. Download the Free Worksheet
A major
.pdf
Download PDF • 483KB
4. Play the triad on a piano or keyboard app.
Update: 23/08 a sharp added to the worksheet that was initially missed. Thank you to Ava and Ruthie for spotting it.