Evolution isn't a theory, it's a fact based on the observed reality of the fossil record. There are theories about how it occurs. Natural selection is the most widely accepted theory of how evolution occurs (an early 20th c competitor was Lamarckism). Natural selection is falsifiable- one would merely need to show that genetic mutations are never beneficial to an organism, or that these mutations are acquired (Lamarckism) in the lifespan of an organism. Clearly the evidence is in favor of natural selection, but the theory of natural selection itself has undergone several major revisions over the past 100 years as a result of new evidence and a closer examination of existing evidence.
To the contrary of your assertion, I know several evolutionary biologists, and they are all thoroughgoing Popperians.
Unfortunately in modern education (and the mass media) evolution, natural selection, and abiogenesis are mixed together as a single concept. So Darwinian natural selection based evolution is seen as the explanation for the origin of life -- something even many evolutionary biologists would have a hard time supporting or justifying.
Natural selection clearly plays a major role in evolution, but it also isn't the only factor. The existence of domestic animals, like cows and dogs, certainly can't be explained by natural selection. Nor can the existence of modern commercial hybrid plant species. So clearly other factors are involved, at least since humans became active on the planet.
Interestingly, I know of no researchers today who can accurately define a test which can identify biological entities designed and created in labs by humans, which one would assume would be "intelligently" designed. If you can't identify a living genetically engineered and created organism how would you expect to know if other organisms were or were not "intelligently designed"?
There are also cases of simple organisms that modulate their development based on their environment - which is essentially Larmarckian evolution, although apparently the organisms retain the ability to grow into multiple forms. This ability, if widespread, adds quite a bit of complexity to the simple natural selection models.
And a theory which says "life must have begun as a result of a lot of random molecular interactions which ultimately ended up producing a living organism" isn't much of a theory. It really has no more basis than someone that says "life must have begun as a result of some space ship arriving on earth and leaving organisms here". Both rely on a long statistical chain of events. To really dig into the origin of life requires a very deep understanding of how molecular biology works, probably more than is now available.
Instead of schools wasting time fighting over what shallow "theory" or "fact" they teach, they should make an effort to teach the students about what the various theories really mean, and how one might go about testing, understanding or evaluating them. Hopefully those students will go on to advance our understanding of our world and how life began.
(Denny Crane: "I Don't Want To Socialize With A Pinko Liberal Democrat Commie.Say What You Like About Republicans. We Stick To Our Convictions. Even When We Know We're Dead Wrong.")