This task should be periodically planned. Sometimes it ends up happening at the most inopportune moments. So, try to plan regularly. But be prepared to do it at the drop of a hat. 

Most appliances are electric and should be unplugged before moving them. Some appliances are in very tight spaces and require two people to manipulate them. You may decide you always want to be present when your teen performs this task. I find it helpful to have them climb behind the appliance once we pull it out and do the cleaning while I hand them all the equipment. 

Pull out the appliance and use the vacuum cleaner brush attachment to clean the dusty sides of the appliance. This is an essential step in cleaning refrigerator coils. This is also an excellent time to detach the dryer vent and vacuum it out. Then clean the floor where the appliance was sitting. Trade the vacuum cleaner for  Windex and paper towels. They can spray the solid sides of the appliances, the floor, the baseboard, and the walls. Wipe them clean. Take a clean paper towel, dampen it with the Windex, and wipe off any excess dirt they couldn’t vacuum off the back of the appliance.   If there is excess dust and dirt underneath the appliance, use the vacuum cleaner attachment to get underneath it before putting it back. Sometimes tilting the appliance one way or another will allow you better access underneath it. This is not recommended for the refrigerator for apparent reasons. 

Doing this for all movable appliances on the same day is a good practice. Cleaning behind appliances regularly can keep your appliances in better working order. Also, the “surprise” times will not be so overwhelming.