Have students sign a “Computer Use Agreement” before giving them access to machines to hold them accountable for using computers responsibly.
Emphasize that computer use is a privilege that can be revoked to keep students on task and focused when working on computers.
Have a way of preventing students from looking at their computer screens when you need to get the whole class’s attention.
Check out Professor Colleen Lewis’ online Scratch curriculum for ready-to-use CS classroom activities and for ideas for your own curriculum.
Install the offline editor on student machines in your Scratch course in case the online editor is not available.
Create rubrics to grade complicated assignments so that both you and your students have a better understanding of what quality work looks like.
Give students guided notes (i.e., partially-completed notes that students complete) to help them stay engaged and learn from lectures or readings. It may be especially helpful to include vocabulary lists.
Use worked examples (step-by-step demonstrations of how to perform a task) to introduce new problem solving skills to students.
Don't worry about trying to match the modality of your instruction to students' "learning styles" since the importance of learning styles is a myth.