One note at a time
I always incorporate some kind of ear training in my classroom. One game I like to play is one note, one shot. Students have to try and play a note in tune by placing the finger quickly and then see it they are in tune with the tuner. I have noticed by the third time on a particular note the students were either much closer or in tune with the tuner.
The purpose is for the student to see their intonation tendencies if they are more likely to play flat or sharp. The students seemed to enjoy this method because they wanted to beat out the tuner and get it right the first time. This also got the students to be more aware of finger placement on the instrument. My students do use tape marking but they understand that it is only a reference.
My students have access to classroom tuners and/or apps for their electronic devices. Students will also work on singing notes to the tuner to develop the ear. When they sing a note is it sharp or flat? I like to use Tonal Energy for my app. Students love to see the big green face that appears. So it is a motivational factor.
I encourage my students to after tuning their instrument, to practice tuning a couple notes a practice session. This can be completed in less than 5 min.
1. Pick a note. Ex. E on D string
2. Put your finger on the note without playing a sound.
3. Make sure tuner is on, then play the note.
4. Check the tuner for your tendency (sharp, flat or in tune).
5. Take hand off, repeat the process with the adjustment until you are in tune.