Second grade math includes solid understanding of place values, addition and subtraction with regrouping, basic multiplication and division such as 7 times 3 or 36 divided by 12 ( using addition and subtraction as basis, not memorized timetables), knows how to read time and count money, has a good concept of various types of measurements (distance, weight, area, etc), good understanding of fractions, can read and create basic bar graphs, and can solve real life problems using all the stuff learned. Like others have mentioned, most kids here might chew through this in a month. But for an average second grader, this is a lot to cover in 9 months. Dd surprised my sister by doing 300 plus 300 plus 300 in her head when she was 3. When I said what's the big deal she knows 3+3+3, my sister who is a teacher told me how much older kids have a problem undertanding this concept. Dd understood most of this stuff conceptually before she turned 4. However, she needed to be taught the mechanics to solve problems consistently. For example, earlier this year, she was trying to add big numbers in her head and getting frustrated if she got wrong answers. I showed her once how to write down the numbers and add using regrouping. She immediately got it and solved about 20 problems in her workbook while I was making tea.
