I don't feel that he needs to be tested for ADHD. If he's interested in something, or if someone makes eye contact with him, he will pay attention. What do you think?
Some kids may appear to have difficulty "attending" during group instruction, when in reality they might have an auditory processing disorder, a type of learning disability that makes it very hard for them to understand what's being said, even though they can hear the sounds just fine. Other kids' minds wander when they are given math that's way beyond their level of mastery. If they don't understand how to do the problems, it's no wonder that they drift and seem inattentive. They see no hope of doing the work correctly and to keep at it may seem to them a waste of time.
Other kids may have dysgraphia, another type of learning disability that makes it hard for the brain to control the muscles of the arm and hand in order to write or draw, or do paper-and-pencil math very well. Their brains function more quickly than their hands. These kids take so much time to "draw" the letters and numbers that they get bored. The creative process gets put in the back seat by this problem with fine motor coordination. Still other kids find it hard to read the social cues in the classroom, and "tune out" because they can't keep up with the flow of verbal and nonverbal communication.
Ask the teachers to tell you more about what they see as inattention. Ask to see the written results of their observations in a variety of settings. It's important to remember that a child can have attention deficit hyperactivity disorder without being hyperactive, so the absence of that behavior does not rule out the condition. However, it's very important to analyze both the learning strengths and weaknesses of a child, and the demands of the classroom or the environment, as well as the style of teaching before anyone jumps to the conclusion that ADHD is the culprit. (Remember that boring teacher, Mr. Yawn? Enough to drive anybody to distraction.)