Thankfully, if a child is accelerated based on both achievement and ability (as the IAS suggests), the rapid learning that has gotten them to where they are will continue to allow them to catch up quickly. When DD subject accelerated and then grade accelerated there were gaps, I'm sure, but she was still way ahead of many students who were matriculated with their grade despite having gaps of their own. And she filled in the gaps with seemingly no effort. DS6 is going to be math accelerated this year (in 2nd doing 3rd grade math) and, based on the end-of-second-grade math test he took last year, the only concept he didn't know was rounding. It just hadn't come up yet. So, in the pool one day I took literally about 3 minutes to explain rounding and the gap was filled! [I should mention that none of the teachers we worked with in deciding on the acceleration was one bit concerned about gaps. I'm lucky to have a great school in this regard!]
