Dan Meyer has created a spreadsheet on which he has listed the Three Acts of many math tasks.
Act One is the video or image of a situation that generates questions that can be answered mathematically. In Act One the student asks a question and then determines what information is needed to answer the question.
Act Two gives further information that may help answer the question.
Act Three shows a video or image that answers the question.
In this spreadsheet, a common question is posed based on Act One and then Acts Two and Three are based on that question. There may be other questions posed that this particular Act Two and Three do not answer. That does not mean that the question is not the right question. It only means that more research will be needed to find the information that will be needed to ask the question.