Mastering facts within 20 and column addition/subtraction within 100 (both with and without regrouping).
The Kozlova/Rubin materials are known for "non-standard" problems that require logical thinking rather than just calculation. Practice Resources zadaniia po matematike 2 klass avtor kozlova rubin skachat
Solving multi-step word problems involving "more than" or "less than". zadaniia po matematike 2 klass avtor kozlova rubin skachat
Basic geometric tasks, such as finding the of shapes. Logical & "Non-standard" Tasks: zadaniia po matematike 2 klass avtor kozlova rubin skachat