I hear two questions:
1. How to address the hitting at preschool (which you are hypothesizing is attention-seeking).
2. How to address his academic needs.
I'm not sure if you are actually asking both questions, but I think it may be useful to separate them anyway!
Question 1 does not require getting into question 2. All that really requires is sitting down with the teachers and describing your observation and hypothesis that he wants attention, and is obtaining it by hitting. This is a very simple and common function of behavior in small children, regardless of cognitive level. Solutions will involve two things:
a) meeting the need for attention.
b) replacing the undesirable behavior with a socially-appropriate one.
The preschool setting can address these by setting up a bit of one-on-one time for him--IF HE DOES NOT HIT. I would suggest having a conversation with him about ways of seeking attention or requesting assistance (i.e., with polite, respectful words). The interval of not hitting required for a few minutes of one-on-one attention will depend on how frequently he is hitting right now. If he hits once or twice a day, then I would say special time should occur once or twice a day. If he hits more than that, then the intervals might be as short as 15-20 minutes. The idea is that it should be an interval that allows for him to achieve the reward about 50-75% of the time, so he experiences positive reinforcement, but does have to work a little to earn it. Once he tops 75% of the time on a regular basis (say averaged over a week), you can start to fade the reinforcement, by spacing out the intervals a bit at a time, until the behavior is no longer a concern.
The setting also needs to make the existing behavior ineffective--which is how time-out is supposed to be used. If he hits, rather than being pulled aside for a little chat, he should be moved quietly and firmly to some place by himself, for, say, 2 minutes. Quietly is extremely important. If the adult engages with him at all while moving him to time-out, it defeats the purpose. This also has to be part of a conversation before the fact, so that he understands that, when he hits, he will immediately and silently be moved into a quiet chair for two minutes.
In combination, he will end up being rewarded with attention for periods of not hitting, and removed from attention when he hits. During the first week or two, the behavior may actually increase, as he attempts to escalate what previously worked to gain attention. Staff must be very consistent and disciplined about not responding off-script.
It is also possible that he will spontaneously extinguish the behavior once it becomes clear that staff will not engage with him when he does it, making the more gradual reinforcement schedule unnecessary.
As to Question 2: perhaps his academic needs are a topic that might be introduced when the school asks what they should do with him for special time.
And yes, we went through something similar, at about this age, except that it was biting. At church.
