Question: If my child does not make progress, should I assume he has limited ability or ask his treatment providers to make changes in how he is being taught?
Answer: If your child is not making progress with an intervention, whether it's behavioral or medical, it is a good time to take stock and to see if the intervention itself is appropriate, or if some other modifications can be made to ensure a better response or more success.
With any intervention, it's important to track the response over time, and different providers will have different approaches, but almost always, it's possible to track data outcomes, so, to measure the number of successes with a certain problem, or to measure the number of times that an unwanted behavior is occurring over time.
If a medication, for example, is being explored for a problematic behavior and there does not appear to be any movement in the right direction, it's absolutely an appropriate time to bring this back to the provider, to have a discussion about whether the medicine itself is the right one or whether the dose is adequate, or whether the problem that was identified as a potential target of the medication treatment is one that might actually better be addressed with another strategy, say a behavioral intervention.
Overall, the approach should always be that you should be able to see that things are moving in a direction that makes sense for you, and if not, that you should ask why it is that we're not making the progress that we had hoped, or what can we do to move things back in the direction that we all want to see them moving.