Get your 2nd grade students using mental math when finding unknowns in addition and subtraction equations with these winter task cards. Students will love practicing adding 10 or 100 with this resource. Students will see an addition or subtraction equation with an unknown addend and will need to use their number sense, knowledge of place value and addition/subtraction skills to determine what the missing addend (either 10 or 100) is. These task cards include an easy to print version as well as a