They tell the students a bunch of things that are really dangerous to do.
They go further than that: the standard textbook includes a horrifying animated photograph of a murder victim. The idea that Transfiguration can be used as a weapon is taught in the very first class session.
In the wood-shop class which I took when I was a year or two older than a Hogwarts first-year, we were taught that the tools are dangerous. We were taught that you can cut your arm off with a bandsaw if you behave foolishly near it; and that if you lower the drill on the drill-press against your hand, it will put a hole through your hand. However, we were not specifically taught about the possibilities of shop tools for intentional murder. It was assumed that any accidents would be just that: accidents.
Now, Transfiguration is more dangerous than shop tools; Transfiguring a brick to air or water could sicken or kill quite a few people, whereas a belt-sander is really only dangerous to those within shoving distance. But a shop-class student casting around for a weapon would probably seize upon a chair-leg or two-by-four much more readily than a saw-blade. The Transfiguration student — having been explicitly instructed that the art has been used to intentionally kill — would much more likely bring that to mind.
They go further than that: the standard textbook includes a horrifying animated photograph of a murder victim. The idea that Transfiguration can be used as a weapon is taught in the very first class session.
In the wood-shop class which I took when I was a year or two older than a Hogwarts first-year, we were taught that the tools are dangerous. We were taught that you can cut your arm off with a bandsaw if you behave foolishly near it; and that if you lower the drill on the drill-press against your hand, it will put a hole through your hand. However, we were not specifically taught about the possibilities of shop tools for intentional murder. It was assumed that any accidents would be just that: accidents.
Now, Transfiguration is more dangerous than shop tools; Transfiguring a brick to air or water could sicken or kill quite a few people, whereas a belt-sander is really only dangerous to those within shoving distance. But a shop-class student casting around for a weapon would probably seize upon a chair-leg or two-by-four much more readily than a saw-blade. The Transfiguration student — having been explicitly instructed that the art has been used to intentionally kill — would much more likely bring that to mind.