Children need a routine. If they have no regular school to go to it means they are no longer in their normal routine. Encourage children to get up and dressed at normal times. They need to have regular breaks from their online lessons and get outside between classes and after school. They don't need to have play equipment in the back yard. If you don't have the equipment, make your own.
Encourage mobility when you can. This may be running around, kicking and throwing balls. Make an obstacle course, maze or an outdoor cycle track (using chalk) or even a mountain bike track if you have room in your yard. Set up a treasure hunt.
Play family games such as backyard cricket, croquet, golf, baseball, soccer or rugby. Play quoits, Kubb or Bocce. Set up a basketball hoop. Look at the old-fashioned games such as Hula hoops, skipping ropes, elastics or hopscotch.
Indoor games can become outdoor games. Ideas include Checkers or Tic-Tac-Toe (Noughts and crosses) The shapes can be made with ropes.
Indoor games such as table tennis can be easily made using the kitchen table, a net, bats and a ping pong ball. Balloon volleyball or sock hockey.