Here you go, the story of Cool (not his real name, but similar "feeling"). Edited when I saw your clarification of grades, not behavior, but the story still goes for both..........
Cool came to me with a long list of misbehaviors. His first grade teachers apologized for sending him to me, but said I was the only one who they thought could handle him in second grade. I had teachers from PK and Kindergarten coming up to ask "Who got Cool this year?" I had teachers from upper grades asking, "Who got that kid, what's his name, the one that......................." whatever followed, it was always something Cool had done.
Cool had refused to work, disrupted lectures, thrown furniture, destroyed books, run away mid-day, ripped down bulletin board displays in the hall, thrown his lunch tray, set off fire alarms, attacked the teacher and other students and so on. Cool failed 1st grade, but his teachers placed him in 2nd because they said he COULD do it, he just wouldn't.
Cool was behind in his studies.........not far behind, but just enough that he recognized it. This is why Cool wasn't doing the work. Cool, I soon found out, was a perfectionist. If it wasn't going to look perfect, he ripped it up. If it wasn't going to get a 100, he threw it away. I began cutting his papers into fourths, and having him do no more than 5 items at a time. Cool then felt he had more of a chance to do well, and if he threw some away, I still had the rest of the assignment.........enough to see if he understood.
Cool disrupted lessons. I had Cool illustrate what I was saying. He loved to draw, so he drew what I talked about. After the lesson, we'd post his drawings as an easy to follow guideline. Cool later said he felt very smart, like he was a teacher, when he did this.
Cool had to have a checklist of behaviors. Cool did NOT know what were acceptable and were unacceptable behaviors. I gave Cool a list of dos and don'ts for common situations. He was required to keep it with him all day in his pocket. He'd put it in his school box at the end of the day. Cool had a table with goals for each subject area listed. Cool got a sticker for each time he met a goal during each subject. Cool started off with days of no stickers at all, then a few here and there. By the end of the year, Cool asked me not to give him his table anymore, as he was getting all stickers anyway and didn't need it now.
Cool was identified as gifted in his second grade year. We had to use a variety of tests, due to his getting frustrated when he began missing questions, and we had to do it over several weeks. We explained to Cool what the tests were for (we don't usually do this, but I felt it was important), Cool later said it had never occurred to him that anyone would think he was smart.
Cool played the clown in class. I got him a study carrel and put it near the door. I always teach with my door open. I enjoy an open door. Because Cool was near the door, other staff members walking by would often stop to correct him, redirect him, point out a mistake. I posted a sign in the lounge to continue, but also to find reasons to praise him and acknowledge when he was on task. Cool later said he never realized so many people cared about whether he was doing his work or not until I put his desk by the door.
We put Cool in our afterschool program so he was out of trouble and got his homework done. We gave Cool's mother a list of counseling places she could take him to, and she got him a bimonthly counseling appointment. His home life improved.
By the end of the year, Cool was working on grade level in most subjects, and above in reading. Cool was able to accept Bs, but mostly got As. Cool was the one child that all the other children said they wanted in their class for the next year. Cool had become a helper to others and exhibited a caring attitude towards anyone in distress.
I was extremely careful with his 3rd grade placement. He had absolutely no trouble whatsoever in 3rd grade. I did not talk to his teacher about his past issues, but did share with her some things that worked well with Cool as he liked to feel helpful and needed. I talked with her about some of the ways Cool had learned to cope when he was feeling bad about himself, and that the counselor was there for him whenever he felt he needed her. Later, when his 3rd grade teacher did find out about his past behaviors, she said he wasn't that child anymore.
Cool is now entering 6th grade. Cool has had NO discipline referrals in the rest of elementary school. Cool continued to improve in school, passed all his state tests, and got commended performance on reading. Cool is known in his trailer park for helping younger children with their homework. Cool wants to be a teacher.
HTH!