My son and I were talking yesterday morning and as a wise ten year old 5th grader he came to the conclusion that he could have just attended the even years of elementary school. K,2,4 and skipped PreK,1,3,5. He did skip 3. He was musing on if the other even grades should have been skips or just stayed home that year. I pointed out he had the Best Second Grade teacher of all times and he wouldn't have wanted to miss her and he agreed. He would magically have moved her to 4th (which she teaches now).
I think the even year plan is great. K,2,4 for elementary...6 and 8 for middle (and here most gifted 8 th graders are taking for credit a hs math class (either algebra or now geometry), a high school science, and sometime a high school business/computer introductory course. Or another STEM/engineering intro course (so they have the prerequisite for higher electives in high school that first year) so for the most part 8th grade is half 8th half 9th grade.
Then you have 9th and tenth grade and if lucky can take advantage of dual enrollment or eary college or APs or some combination.
