This is a book by behavior change researcher John Norcross that gives a non-technical guide to creating and sticking to a plan to change - for example, a plan to keep your phone out of sight during class time:

Changeology book and resources

This is a book by teaching expert Linda Nilson on self-regulated learning:

Creating Self-Regulated Learners

Here are some apps designed to help you either keep your phone off during specified times or lock out distracting web sites:

Pocket Points app

Flipd app

Self Control app

Freedom app

Cold Turkey app

Forest App

In the Attention Matters! module, we ask students to write a brief reflection at the end explaining what they plan to do differently (e.g., turn their phones off during class) and what strategies they will use to stick to the plan when it gets challenging. We also have them discuss this in an online forum, along with other issues such as how to handle classmates who are being distracting during class.

University of Texas professor James Pennebaker reports that replacing traditional assessments with a daily routine of frequent assessments not only improves performance, it reduces the achievement gap for less advantaged students and produces lasting gains in other courses the student is taking. This may be because this approach motivates students to study more frequently and improves their self-regulated learning skills. For details, see this article.

You can also create a whole assignment around intentional behavior change, focusing on managing tech use or any other type of change students want to make. Here is a sample assignment.