When it is time to review counting atoms, try this sort to help students review. There is an added bonus of the name of the chemical compound that can be given as an extension to the activity. The teacher will cut these out ahead of time and laminate for longer use or just use as is. Place cut up pieces in a baggie and have students match the formula to the number of atoms. The name of the compound can be given at the same time or as a challenge students can try to figure out the formula when they have correct numbers and formulas.