For science, my teacher wants us to write a children's book from the pov of a cell after a character gets hurt. I already wrote about a mouse breaking her ankle from ballet, but I now need to write from the pov of the bone cell.
A good place to look is the film Osmosis Jones and it's spin-off TV-series Ozzy and Drix did something similar. In the setting, Osmosis "Ozzy" Jones is a white blood cell inside of Bill Murry (in the film, in the Cartoon series the human is changed to a 13 year old boy so as to be relatable for the target demographic), and deals with various health issues. This plays out like a "Buddy Cop" film... only when the cowboy cop says "Crime is disease, and I am the cure!" it's more literal than most. Most organs are given a city analog function (The brain is City Hall, dreams are shown in movie theaters, the white blood cells are cops, certain bacteria are informants in the Vaccination Protection Program, the nerves are telephone/power lines, ect.
It might not be something to directly copy, but it's an idea and not an original one at that (Disney World's now defunct Cranium Command took a similar premise, but instead of a city, the personified internal functions are treated as piloting a human mech ALA Star Trek, and pre-dates Osmosis Jones by at least a decade. Inside Out got accused of ripping off Osmosis Jones even though the film portrayed only aspects of human thought and psyche, rather than the more biological aspects of the the other two. The director did name Cranium Command as an inspiration.).
I would start with the end, and make the rest fit the conclusion you want to reach.
How close to the current scientific theories will work for you readers? How much personification do you need to make it relatable? Do you present the role of a single cell, or of several cells of different types?
It can be hard, even for adult science-minded people, to avoid personifying cells. We tend to ascribe motives and missions to things that have a absolutely limited scope of action and knowledge. For instance, an immune system B-cell doesn't "seek and destroy". It bumps into things until something sticks, and the sticking causes it to release some bubbles of chemicals it has been accumulating. It may also cause the B-cell to replicate. None of this makes a good children's story full of happy, smiling cells, but it could be used to fashion a tale about how many people just "keeping their heads down" and "doing their job" can make the whole organism work smoothly.
If I were trying to write a child's book, to avoid the idea that any single cell knows the whole story, I would use an omniscient narrative voice that introduces individual cells doing their jobs. From the omniscient point-of-view, I would try to show in an entertaining way how the simple jobs hook together. For conflict, I would add a defect. A virus would be typical -- maybe a COVID virus -- but perhaps a skinned knee would be more relatable. The simple jobs would shift to a more active, higher gear, the conflict resolved, but only the omniscient narrator would be able to see the whole picture and comment on the restored health.
But, I am not a children's book writer.
I recommend taking inspiration from Rooms Full of Me, a story about a sentient virus. It's a bit disjointed, but I personally feel that it captures the perspective of such an entity fairly well.