I would use QR Codes in the classroom for a number of activities. Whether it was literacy, math, science or any subject, QR codes get students used to using technology in a fun and creative way. The student would grab a cube and complete each of the activities as part of a daily task. I would use this in my 1st grade classroom.
factions to decimals: Crack the Mission 2110 vault using your knowledge of fractions and decimals. Students get their briefing (including a short description of how the conversion is performed) and must solve a series of problems to unlock secret doors and compartments.