Introduction

Green screens have been around for some time now.  In very simple terms, green screens provide a transparent background behind an object (such as a person); the final background image is then superimposed creating the illusion of the person actually being there. A classic example is weather reporting on TV.

The reason that bright green is used is that there are no green pigments in skin, so skin will always remain opaque when you film. However, if a person wore some green clothing, it would become transparent and let the background shine through- with interesting effects! 

As technology advances, it is becoming incredibly easy to harness the potential of green screen techniques in the classroom.

Equipment Needed

All that is needed for green screening is a green background- you can buy green cloths; you can paint a wall matte green; you can buy pop up frames; or in schools, you can use green backing paper! A mid green colour works best.

The more even the green background, the better the final result will be. If you use cloth, hang it a couple of hours before use to let the creases drop out and use some weights or clips to stretch the cloth. You could also mist the cloth lightly with a spray to help the creases fall out, although test on an inconspicuous part as water will darken the fabric.

Good lighting will dramatically enhance the final result too.  Photo studio lights with daylight bulbs will improve filming if it is in a dark room with yellow lights in the ceiling. If a classroom is naturally bright you should be fine.

Software

For iPad there are great green screen apps- my two favourites are:

Both are extremely easy to use, although they work in slightly different ways.

With Veescope you choose your background first; then film in front of the green screen.  Both the background and the subject are merged together at the same time. It is good for on the fly work.

With Green Screen by DoInk, you can separate the clips; you can film against a green screen first, then bring the green video clip into the app and add the background (or backgrounds).  The significant advantage is that the background can be changed if it is not right, without having to film all over again. Another great advantage to DoInk's app is that you can adjust the green using the colour dial to remove all traces of green.

The possibilities of green screen are endless and there are so many applications across the curriculum. Fantasy, pupils describing settings; non-chronological work; news reports; any work that is prefaced by you asking the pupils to "Imagine...."; pupils explaining properties of shapes in maths... and for real impact pupils need to learn how to pretend and act!

Happy green screening!