This is the third practice but this time you will find 5th intervals. Rehearse till you can get the right pitch.  To get the best tuning, practice with these exercises. You will have to raise or lower the pitch of the notes. Then you will be able to do the same with the proposed exercises.

Here's the sound file you can use as a guide.

When you finish practising, study and memorize the staves in the exercises below and find the 5th intervals. Then sing the notes aloud according to their pitch and keep the right time signature with the corresponding hand movements. Click on the question mark to check where the 5th intervals are.

Exercise 1: 5th intervals.

Use the sound to see how well you are doing.

Exercise 2: 5th intervals.

Again there's a sound file and the video score to check your improvements.