I am not sure to which textbook you are referring. However, decimals and possibly long division are part of the regular third grade curriculum. My oldest ds covered both topics in second grade while in an acceleratd program doing 3rd grade math in public school. My younger DS covered both as a second grader while accerlated to 3rd GT math (compacting 3rd and 4th grade). My DD covered decimals in the fall of 3rd grade GT Math (compacting 3rd/4th grade) and is covering long division in the 4th quarter. I am sure that decimal is a third grade math topic although it actually was introduced as money in second grade math. I think long division is still also a third grade topic but it is possible that it may be consider a fourth grade topic now.
