The IEP needs objective measurements. We'll try to increase from one minute to three minutes. Parents should always observe a child's evaluation if their presence will not adversely affect the child. Evaluation results become part of a student's permanent record and it impacts placement and expectations, so it needs to be as accurate as possible. There can be unusual disruptions or distractions.
Parents can step in and help.
For example, when my child was evaluated at the start of the school year, it was very hot, the room was full of distractions, and he wasn't positioned for his body to work optimally. There were constant intercom interruptions, people carrying on discussions in the room and signs falling off the walls. When it was over, I made it clear that the evaluation needed to be thrown out. Parents should push to have your child interact with typically-developing kids. If a child placed at special school doesn't interact with typical peers, parents could request that the child attend local school assemblies.