Students learn about dark matter and dark energy, as well as the role they play in the expansion of the universe. Then, they will model the expanding universe using balloons. Materials Balloons Small round stickers (five to 10 per group) Felt-tip marker Ruler (Optional) balloon pump Management Gather enough materials to provide each group with a full set of materials. Have extra balloons available as some will pop. Consider incorporating the demo How Do We See Dark Matter? in Step 2 of the Proc