Meet the mysterious dog agents – they’re smart but quiet about their secret missions. This time, they need your help sorting their case files by answering addition and subtraction to 20 questions.   This PowerPoint activity is a great practice game for answering addition and subtraction questions. To help the dog agents sort their case files, click on the number generators in the brown folder. Afterwards, have your students answer the addition or subtraction equation by numbers up to 20. If they answered correctly, click on the “Agent’s Folder” button to place the case file there. Otherwise, click on the “Trash bin” button.   To preview how this game works, watch the video below.