Begin by teaching the children how to read rhythm aurally. Teach them only the most basic rhythms: whole notes, half notes and quarter notes. Start a metronome and have them clap on each click for the quarter note, every other click for the half note and every four clicks for the whole note.
Continue teaching rhythm by showing them what each note looks like. Pass out music that gets progressively harder. Begin by showing them only quarter note music. Add half notes once they understand the quarter note, and finally, use whole notes. Make sure to teach them about rests as well.
Start teaching the children about pitch notation after the first week. Since they are children, all of them will sing in the treble clef. Have them remember the spaces on the staff by using the following trick: "If you look between the lines, you see your FACE." Explain that the spaces spell the word F - A - C - E.
Teach the names of the lines of the treble clef by using an acronym. A good acronym to use is "Every Good Boy Does Fine." The first letter of each word is the name of a line.
Explain that the correct way to breathe is through the diaphragm and that the children should never force a note that is too high. If a child is having trouble singing a part, give them a higher or lower part to sing.
Perform musical scales with them. Start with major scales. Pass out sheet music that lists the scales and have the children sing each pitch on a whole note. Practice the major scale until they can sing it without the use of a piano.
Present the children with simple stepwise music. Tell them that when the notes go up, they will sing higher. When the pitch goes down they will sing lower, just like with the scales they learned. There is a good deal of music written for children that uses stepwise motion.
Provide them with more difficult music only after they have been singing together for several months. You can begin to select music that has skips and even leaps between notes once they get a solid understanding of how to sing stepwise music.