There's hope for your kid do not despair!
In third grade I was at a new school and it was more of a hippy style of learning. I had two teachers and we were housed in an "open classroom" the divider doors open to one conjoined room with at least 40 kids. There was a make-believe jungle with things hanging from the ceiling. I have fond memories of feeling free as I ran around the room pretending to be a monkey. One of the teacher's was more academically inclined than the other. She would give out assignments and expect us to finish them. I was quite unruly and would just skip them or give them perfunctory attention, having little interest in what was required to complete them. Any piece of work with a "bad grade" would go into the garbage. When my parents asked about how I was doing. I would reassure them well! and I thought I was.
During story time and share, I would make up tales that we took exotic trips during school vacations that mimicked some of my peer’s stories. The teacher's seemed to take a keen interest in my made up account of what I did during the breaks as they later brought them up to my parents during the teacher conferences. When my parents got home they were furious with me that I not only fabricated stories on how well I was doing but also was telling people about trips that we hadn't taken. I think my father was especially upset him being a teacher and all.
My mother was all about truth telling. She tried to hit home in me the importance of being honest and the importance of being conscientious in my facts. She gave the example of the book The Boy Who Cries Wolf, and how when you lie there might just come a day that no one believes anything you say and then you are in big trouble. I did find the book intriguing and mildly disturbing and tended toward honesty after that.
My older sister who had her own struggles found the book downright traumatizing and after hearing it just once, requested to hear the story over and over again for years afterwards.. Each time the story was replayed she then had a million questions on why did the boy get eaten? We all needed to reassure her that the wolf wasn't coming to get her. Well not unless she trailed off from the truth....