You can only know what I tell you about on this site.
Which is why people have been confused as to what exactly it is you're trying to do. So there's no point in snapping at us.
Science fiction made science more interesting than the science teachers I did not get until high school.
Yes, we know, because you've told us this many times before.
And none of my teachers selected or gave it to me either.
That's because the educational world was prejudiced against category market science fiction as trash that was not appropriate reading material for children in 1959. The Hunger Games was published into a whole different world. My daughter's school reading lists, a decade ago, were studded with SF and fantasy works.
But when the teachers are teaching elementary school children English, they are teaching them to read and write. Adding the requirement to check the science content of only some of the books -- the science fiction -- is not particularly useful to them and has nothing to do with assessing the book's reading level for the kids. Teaching them science requires science fact. Teachers in many places in the U.S. are barely allowed to teach science theory and the scientific method and even when they aren't in such counties, they barely have enough time to teach the science material they have to get through in the textbook. Having them throw in some fictional novels is not going to happen.
I've agreed with you in the past that a partially integrated curriculum, especially in elementary where one teacher does most of the courses, in which sometimes a novel in English class could be connected to what's being done in science class, is a good idea. And there are probably counties where that sort of thing is being done, formally or informally. But it is unlikely to form a standard curriculum program at the federal level, partly because it would not be very flexible for different schools to adjust to different needs.
The big issue in English class is getting kids to be able to read any type of book and any type of fiction, not just science fiction. There is fighting over a curriculum because there is always fighting over curriculum. Some people don't want certain things taught due to religious beliefs. Others fear that the curriculum isn't supporting kids who have advanced reading skills enough or leaving those below the average too far behind, or having too low a baseline for the average. There is concern that a particular curriculum teaches to tests and does not properly assess and develop skills. There are arguments over whether one book is best suited to one reading level or another and how you test it. Syllables and sentence length is a very basic measurement; there are other measurements that they use in addition to it. The assessment of these different curriculum by people is on-going and changes with the times.
But hard science content and the number of science words in the fiction used -- some of which is not science fiction or fantasy -- is never going to be a measurement for reading levels because it has nothing to do with reading skills, other than that science words are often bigger words. Whether a science fiction novel is a post-apocalyptic dystopia in which people have reverted back to the stone age and there are very few science words in it, or a space adventure about dealing with a black hole and there are lots of science words in it, doesn't effect the students' ability or not to read the book.
The argument that one SF book gives you both a certain reading level and science content, and therefore should be chosen over another SF novel for reading lists that doesn't have as many science words in it isn't going to work for them. When you are trying to get children to read, you are not going to limit them to SF novels, and you're going to provide a mix of acclaimed and popular novels, SF and other, in order to engage the kids and to expose them to writing that will help them in their reading skills. Many of the older SF novels were not written for children, but for adults. The language in them, not even counting the science words, can be difficult for children who are not advanced readers -- as you probably were at their age. The number of older SF novels therefore tends to increase when you get to the high school students' curriculum, who read a mix of some YA and a lot of adult books.
Educators in elementary school are usually using for reading lists books written specifically for children with specific traits designed to increase and develop reading skills. Harry Potter, for instance, was written for middle school children, and deliberately has repetition, rhyme, silly made-up words and names designed to teach children sounds, etc. -- things that drive adult readers crazy but help kids develop reading skills. Books for junior high and YA fiction drop the linguistic tricks but try to use more complex sentences and issues to further develop not just reading comprehension but writing skills. Many of these books are not fantasy or science fiction; some are. So again, for the main purpose of having the reading lists, hard science content and words are irrelevant.
So again, if you are trying to come up with a system to measure hard science content of a sub-section of fiction for the education system for children, it's not of much use to them. If you are trying to come up with a system to measure hard science content of a sub-section of fiction for adults and others to fine-tune their reading choices, then it might be useful to people who want that sort of information in making their reading choices. Of course ultimately this is something you are doing because you are curious and want to do it, and nothing wrong with that.