These clean, useful posters provide numbers 1-20 in numerical, tally, and word form. It's an easy reference for students, and teachers love that they are simplistic yet informative. They are aligned to the Common Core in that they help with cardinality, rote counting, serialization, and understanding different representations of the same number.
Print them out and put them around you classroom. After I made these, every teacher around the school asked me for them to post around their classroom. Students really picked up on tallies and spellings quickly!