Scoop the hamburger meat into the bag. With the bag still open, carefully begin to roll and press the meat down so that it expands to fill the entire bag in an even layer.
Squeeze all the air out before sealing it in, then use your dividing tool to make grid-style indentations in the burger meat, pressing all the way down and through.
Make sure the bag is lying flat in the freezer. When it comes time for your next barbecue, you can easily break the frozen meat off one square at a time to grab and grill.