Phones and laptops are a common flashpoint. Rather than fighting it case by case, set a clear device policy that fits your course and explain the reasoning, for example that divided attention hurts learning, which the cognitive load research supports. Some classes need devices for the work; others are better without them for stretches.

Whatever you choose, state it up front and apply it evenly. Build in deliberate device-free segments if that fits, and design active tasks that keep hands and minds busy, since engaged students reach for their phones less. A reasonable, well-explained policy prevents the recurring low-grade battle that wears everyone down.