Teach the basics of the music staff. Use a blank sheet of music staff paper and show your students the names of the notes on the staff. The spaces on the four lines of a musical staff are F, A, C, E. The lines are E, G, B, D, F. Teach students to use a phrase such as Every Good Boy Does Fine to memorize the lines and spaces on the music staff.
Explain that notes above the music staff follow the musical alphabet forward and notes below follow the musical alphabet going backward. The musical alphabet is C, D, E, F, G, A, B, and the octave C. Starting on any of these notes produces the same pattern.
Use blank staff paper and show students how to draw a treble and a bass clef. Explain the difference between the two. Draw a time signature and teach your students note values (whole note, half note, eighth note, and sixteenth note) as you explain the significance of the time signature. Explain that 4/4 mean there are a total of four beats to a bar, then demonstrate how to fill each bar by using various combinations of notes (and their equal rest values) to fill several bars. Ask them to repeat the exercise you demonstrated. The best way to get your students to understand musical notation is by getting them to practice right away.
Hand out note and rest value charts to your students and emphasize the importance of referring to these charts until they become comfortable with the musical symbols. You can get these charts from beginning music theory books or online (see resources)
Demonstrate how basic and advanced chords are constructed to help your students identify chords when they run across them in printed music. Guitar chords are often written on a graph representing the neck of the guitar, but piano and other music presents chords in standard musical notation.
Refer your students to a chart featuring the universal music symbols that indicate dynamics, or how notes are to be played. There are too many music symbols to teach your students in a short time, but at least familiarize them with the most basic of these, including the forte sign for loud, the "p" indication for soft, slide and crescendo/decrescendo markings.
Present your students with beginning sheet music and ask them to break it down for you. Having students analyze and teach you what they know is a good way to reinforce what you've taught them. Your job as a teacher is to give your students a strong base to build upon as they continue their musical studies.