This worksheet gives students extra practice in choosing between "will" or "[be] going to" when talking about future plans. There is always some disagreement between teachers for which to use when but the rules I teach in my classes is we use "[be] going to" when talking about a plan that has been scheduled (ex: We are going to go to the park next Friday). I teach that we use "will" for decisions IN THE MOMENT (That sounds fun, I will go with you), THINGS WE HOPE OR THINK WILL HAPPEN (I think he will come to the party/He will probably come to the party), or THINGS THAT ALWAYS HAPPEN (The Sun will come out tomorrow. Christmas will be on December 25th, etc.).
This worksheet is not meant to teach students the rules, they will not be successful if you have not already worked on this with them, it is meant to be extra practice to improve their skills.