First Grade Math Unit 12 Adding 3 Numbers First Grade Math Worksheets ... Oct 13, 2022 - This fun and differentiated JAM-PACKED unit is filled with 215 pages of everything you need to teach adding 3 numbers (with sums to 20) in first grade. (Link to REAL PICTURES & fun ideas to teach in description!) This pack covers 4 main standards/concepts: adding 3 numbers, strategies for adding...