This video from Khan Academy provides an overview for students on how to multiply complex numbers.  https://youtu.be/cWn6g8Qqvs4

When teaching operations with complex numbers, have students complete this two truths and a lie activity to demonstrate their understanding.  https://docs.google.com/document/d/1jOoQZlOIBWHDKkvFspQwSm9menmr7p6DnsXI1tO0PZ0/copy

This quizizz that can be used as a team game or independent practice would be a nice way to get a quick check on student understanding.  https://quizizz.com/admin/quiz/57c57fe4986afafe8367ce0a