Show a six-year-old 12 + 2, and some will count on from twelve while others freeze at the two-digit number. Both reactions make sense, because teen numbers are new territory. This 1st grade teen number addition worksheet offers a calmer path. Seven vertical sums sit in colored boxes, each with a small header for tens and ones above the digits. The first box is a worked example, 13 + 5, with a note in the margin: add the ones, 3 + 5, then bring down the ten. The six sums after it follow the same pattern, from 11 + 4 to 17 + 2. No sum needs regrouping, and every total stays within the sums to 20. A second page gives the answer key.