Elementary school is (or used to be back when I was there) 1-6th grades, and in 6th grade children are 12 years old, I believe. There used to be something called a 6th-grade exam (testing both polish and math) that everyone took before going to middle school, which is what I was looking at before. Though some of these questions may be in the training set, so I would advise to scramble the numbers. Here's an example: https://arkusze.pl/sprawdzian-szostoklasisty-probny-operon-j...