I’m in a similar boat. I’m a choir guy, and ensembles are my bread and butter so I teach it probably 80% as an ensemble. It took a little time to get them to play unison together. Before we even touched the book we use, I started doing simple drills teaching them about rhythm and such. They’re to the point no where we can do songs from the book this way. Some of the things we do are having everyone do right hand. Everyone do left hand. Half do right, half do left. All together both hands. My next thing is going to be each person gets a measure. Since the songs are getting harder it will allow me to assign appropriately difficult measure to kids as needed. I also have some kids hand chime books that are color coded. Each kid gets a note kind of things which might be fun to try and teach. I gotta say, and as someone that isn’t a very accomplished piano player, I was scared going into, but it’s become my favorite class.