Octave and subtracting a semitone. In a short time the thinking of other tones will not be required.
It should be clearly understood that the even intervals occupy a space and a line; the uneven intervals either two spaces or two lines. It is readily grasped at sight that
![\relative f' { \override Score.TimeSignature #'stencil = ##f \time 3/1 f1 c' }](http://upload.wikimedia.org/score/t/d/tdtcli1h31e5babqv2l5e9pbyakmrwa/tdtcli1h.png)
cannot be a 4th or a 6th.
To reach a 7th, strike the octave, and come back one, then sing the 7th direct. The addition or subtraction of a semitone, by the use of a sharp or flat, can be practised, and the names of keys and numbers of sharps and flats can all be added. (See "The Choir-Boy's Manual," companion-book to this.)
When the choir can sing the seven intervals of the octave, starting from a given keynote, they will, if attentive, count up from any other keynote and sing equally well.
On the blackboard mark a keynote, then all the uneven intervals, 3d, 5th and 7th, then the even ones, 2d, 4th, 6th, 8th.
![\relative c' { \override Score.TimeSignature #'stencil = ##f \time 4/1 c1_"1" e_"3d" g_"5th" b_"7th" | <c, d>_"2d" f_"4th" a_"6th" c_"8ve." \bar ".." }](http://upload.wikimedia.org/score/r/k/rkkutzhs5d25qrs6jz7zxuyrbo68qcg/rkkutzhs.png)
![\relative e' { \override Score.TimeSignature #'stencil = ##f \time 4/1 \key e \major e1_"1" gis_"3d" b_"5th" dis_"7th" | <e, fis>_"2d" a_"4th" cis_"6th" \override NoteHead.style = #'harmonic e_"8ve." \bar ".." }](http://upload.wikimedia.org/score/b/p/bphbxadzsttk0kzzst8f0ho0ckemxoe/bphbxadz.png)
![\relative f' { \override Score.TimeSignature #'stencil = ##f \time 4/1 \key f \major f1_"1" a_"3d" c_"5th" e_"7th" | <f, g>_"2d" bes_"4th" \override NoteHead.style = #'harmonic d_"6th" f_"8ve." \bar ".." }](http://upload.wikimedia.org/score/k/y/kyj0sdbgjsp7b7u54984vweh9aq2pm2/kyj0sdbg.png)
Pupils should now be able to name the interval from the keynote, by placing a series of notes on the board and pointing to them, thus: