String some beads on a few pipe cleaners in order to avoid scattering or losing the beads.
If there is sunshine, let students take the beads out to a window or outdoors to see the beads change color. Tell them to see if the beads change color when placed in the shadow as well (due to scattering of UV light by the atmosphere).
Turn on the black light and show how the UV beads change color strongly when placed under the black light.
Apply sunblock on a transparency film and place between the black light and beads to show the absorption of UV light.
Apply cream cheese on another film to show that even though it is opaque, cream cheese does not block UV light.