I wish this existed when I was a poor college student without a DSLR or a proper cinema camera. It’s best to experiment in the field with a real camera whenever possible, but if you’re having trouble visualizing the effects of photography concepts (which also apply to shooting movies), this online app called CameraSim ™ does a fantastic job of simulating aperture, shutter speed, & ISO. It even adjusts the DOF (depth of field) based on focal length and the camera’s distance from the subject. Check it out!
Although this app was intended to demonstrate still photography principles, some of the settings (such as DOF) do update live as a moving image. When thinking about cinema practices, remember that movies are just a rapid series of still photographs just like these. Seeing the noise that higher ISO puts in your image after hitting the shutter button, for example, is very similar to what each of your 24 (or 30, 60, etc.) frames will look like.