One tip I would give (as a kids sports coach): Instead of starting with every student doing a stand up activity simultaneously, start with nominating one student to do a part of the activity in front of everyone as a demonstration for the others to observe. Once they complete the task, you can give feedback to them or quiz the other students asking what feedback would appropriate.
Then you repeat with another few students until everyone understands what is expected. Once they understand, you set them off to try on their own and place a short time limit on it initially. Five minutes is fine because they need more guidance. Break the task up. Once they are familiar with the exercise structure, you can go longer time and more complex.
Don't expect them to succeed. The point of exercises is to build up slowly from low ability. Give praise for what they got right and make a note of where they can improve.
At 13yo, kids are still learning how to study or apply their knowledge.
Yeah I agree. Games are just to de-stress their brains, especially at the end. As long as they are implementing the rules and spirit of the game, you've achieved your goal.