Download the sheet music for this exercise from the ViolinSchool library at:
https://www.violinschool.com/library/on-the-straight-and-narrow/

This exercise helps you to avoid going out of tune when moving your finger from one string to the next.

As we move the first finger towards the E string, it becomes slightly more curved, which can create a tendency to play flat as it moves in. The opposite happens when we reach out towards the G string. The finger straightens out and it's easy to accidentally play sharp.

To stop this from happening and to stay in tune, we have to make sure that the finger lands in the same place on each string.

We do this by thinking ahead about where the finger is going to land, taking into account the change in the angle of the finger.

A little bit of swing in the left arm will help you to play comfortably on each string.

Your elbow moves in as you swing round to reach the G string, and out as you swing back around to the E string.

Play along with the piano backing track and listen to whether the pitches you're playing fit with what you're hearing. This will help you to know whether you're playing in tune.