2nd Grade – MATH CARDBOARDS – CLASS SET – 30 sheets/package ADDITION AND SUBTRACTION TO 20 – 4 packages (BRAND NEW – STILL FACTORY SEALED!) Publisher: Houghton Mifflin Copyright: 2012 Pages: 30 sheets per packaged set (4 sets) **These are great flash cards/teaching tools for Teachers/Homeschoolers/Parents/Tutors!**The flash cards are constructed with heavier cardboard for more durable handling.***The answers can be found on the backs of the cards for the instructor.***They begin more basic, but continue to include adding and subtracting numbers to 20. ****These are a great supplement for virtually any math curriculum! These materials were purchased from a school district’s surplus sale. We ship within 1 business day of receiving payment. Thank you!