Figure out some things he is interested in. You can use those things to draw his attention towards what you are teaching. For example, if he loves trucks or tractors you make a math problem using those. If you are teaching motion or pushes and pulls you can give examples using trucks and tractors. If you teach using things he is interested in he will be more likely to pay attention the first time.

I would have this student help with the instruction. It will keep him focused and show him that he has more to learn without having a negative impact on his confidence.

If the student is refusing to pay attention because he feels that he is too smart then he should learn through natural consequence that he needs to start paying attention. If there is more going on then maybe the teacher should speak one on one with the student and ask what they can do together to help him be successful.

Try to find a way to make the subject matter interesting for him. Challenge him with things he does not know.

I will suggest to have a question during your lesson, that he will find interesting, so he would have to follow along otherwise he would not be able to answer it by the end of class. Having like "exit notes"

I feel it is important to have a conference with his parents. The student may feel that he knows everything, but he needs to take his education more seriously. It is important to document data and present it to his parents. Set up a goal that his parents, you, and the student can agree to so that everyone is working to make the student the best he can be in class. He needs to participate in class and once he sees he has support then that may be all it takes to get him on board. Each child is different and parents can't help if they do not know there is a problem.

If this student is not paying attention, perhaps this student needs to learn the negative consequences of his actions. Has this student said out loud that he doesn't need to pay attention, or is this an assumption? Introducing his parents to this will be crucial. I suggest allowing him to do what he's doing (so long as it's not disrupting the class), without offering the remediation afterwards. Seems like he knows he can get away with it and do it at a later time. Another option would be cooperative learning. Keep engaged with the other students. If he does "know it all" he can be entertained by assisting his classmates.

It may help to truly analyze the situation. Is it a particular type of instruction he zones out during? If so, it may be more about his learning style or even hearing issues. Sometimes students will try to mask difficulties they are having by adopting a superior attitude.

I had this same situation last year when I was teaching gifted and high achieving. I created a table of data showing his scores and how he compared to the rest of the class (I didn't show him any names, just the average). This was eye opening for him because he wanted to be ahead of the class. We had conversations about how when you think you know something, just listen in case there is something new. Every one in and while, I would throw something into the lesson like, "by the way, when you go to your seats I want everyone to turn their chair around and sit. if you do that you will get a treat." I just wanted to see if he was listening and he wasn't. He was the only one that got a treat. I told him that he never knows what a teacher will say so he needs to pay attention the first time.

I have the same situation right now and I haven't figured out what to do. Right now, I'm letting him do it his way, "bomb" it, see his grade, and we redo it. We redo it during this preferred activities time. I'm honest with him and tell him because he wasted class time refusing help and instruction that we have to redo it during his time. I also let him see that other students did their work the first time so they get their free time while he has to redo it. It's helped some but again I haven't completely figured it out.