Oh lets see I know a few that are really good.
Fern Gully has always been a good one for any youngster getting into the environmentalist movement. It is rated G. For those who may not know it is about an enchanted forest that gets hit with loggers and pollution and a forest fairy has to stop the chaos.
One for older people is Watership down is rated PG but shows some pretty gruesome and horrifc battles scenes that can give the kids the willies but nothing too bad but it can be pretty frightening for some of the characters seem to get mangled up pretty bad. It is still pretty good and talks about rabbits protecting their warren.
Some of the Disney films I would recommend are Fox and the Hound which has some really nice characters and is pretty funny. It also talks about the dangers that animals face for there is a hunter by the name of Amos Slade who tries to kill Todd the Fox. It is a pretty good one though if you have not seen it the bear scene might be a little hard on younger viewers.
I am just going to skip Bambi and move on to a Bugs Life. Even though it is not about Hemiopterans it is still a pretty good film. It has always been one of my favorites. It has a lot of humor but of course it has a lot of drama for it is about a Grasshopper gang who has pretty much gone gangster and have enslaved a bunch of ants who think they are getting protection from other insects.
There is others like Ice Age even though they are quite crazy and somewhat adult with their humor there is still some pretty interesting creatures from the Cenozoic era. There are like five or six films in that franchise and are pretty funny. I like them.
The Lorax is a good one.
These will be good to kind of get your kids familiar with some things in a general perspective about certain issues and will help them make connections to the real world and how it works. It will be a good starting place for them to start separating the fact from fiction. I know several others. The Land Before Time is pretty good and will expose kids to Dinosaurs a big which. I also like Disney’s Dinosaur that talks about migration and extinction level events and also has a mix of both Dinosaurs and Prehistoric Mammals. One of Disney’s most underrated films of all time and one of my personal favorites. It is pretty interesting and it does have plenty of creatures and battle scenes that will capture their imagination.
Finding Dory is pretty fun and Finding Nemo are both pretty popular and what not. I would also recommend. I am just going to slip this one in just in case you just want to check it out. Star Trek IV: The Voyage Home talks about whales, whaling and extinction. But I am just putting that out as a good one. One of the more lighthearted of the Trek films and is just genuine fun. So yeah these are my recommendations.