Two video clips, layered on top of one another. See timeline below to view how I layered the clips.
Video 1 (the background layer) = Filmed myself talking to my empty hand as though there was a miniature version of myself standing there.
Video 2 (the green screen) = Filmed myself in front of a green hallway wall with a green cloth on the floor.
Note: I added a pixelated "dissolve" transition in front of my green screen clip (on Video 2) to give the effect that I magically materialized on my hand.
In this clip, I have a hallway in the school painted green (thanks, PTA!) specifically for green screen projects. I used green fabric to cover the floor, so that I would be surrounded by green, and then when I keyed the green out, I had a full standing figure that appeared to "float" wherever I placed it. I also shrunk down the top clip in order to exaggerate the size difference.
Pop-up green screen (check Amazon)
Tablecloths (check the dollar store)
Painted panels, like foamcore, plywood, styrofoam, or cardboard
Green fabric by the yard from the fabric store
Green bedsheet