Friday, October 26, 2012

It's Easy Being Green (If You Have a Green Screen): a guest post by @billselak

It's Easy Being Green (If You Have a Green Screen) 
 by Bill Selak 

I film my elementary band tutorials in a concert hall in my classroom. The concert hall is located in the corner of my classroom and is built with green construction paper. It's called a green screen, and it's pretty easy to do use. Green screening, also known as chroma keying or compositing, allows you to add one video on top of another video. This is how the weatherman stands in front of the map--the editor erases the green behind the weatherman, and the map is on the layer below him. Studios have fancy green screens and fancy lighting, but DIY green screens look surprisingly good.

 To create a green screen, you will need either green cloth or green paper. You can even use green butcher paper from your school's workroom. The goal is to have no wrinkles and no highlights on the green--if you spend a lot of time and money setting it up, the effect will look better. The trickiest part of setting up a green screen is to light it evenly. If one part is darker, the software thinks that it is a different tone, and the green will remain in the video. I recommend either the $9 work lamp from a hardware store or the $100 soft box from Tube Tape. As long as the green is decently flat and decently lit, it will disappear.

Try to keep the actor away from the green screen. Also, make sure your actor is not wearing any green, or it will disappear, too. Once you've recorded the green screen footage, you need software that can key out (or get rid of) the green. You can remove the green on Apple computers with iMovie or on iOS devices with Green Screen Mobile Effects (free app). Record the background or find a photo, then drag the greens screen footage on top of the original clip. It's common to see teachers changing the background for tutorials or news shows. Other possibilities include changing backgrounds to a fictional place, "traveling" to a real place, or using student art. The background can be a still image, which is easier, or a video clip.

Once you show your class a few examples, they will amaze you with ways to integrate green screen clips into your classroom. I recommend showing them professional reels and student-created clips. It could also be useful to teach your students about the history of green screen technology. How else have you seen green screens used in the classroom?

Visit Bill on his blog,
and on Twitter @billselak 

A special thank you to Bill for composing this post for my site.  Congrats on getting accepted into the Google Teacher Academy - well deserved!


  1. Awesome blog post! No doubt cool and amusing. I have discovered much useful stuff out of it. I’d love to go back over and over again. Cheers!

  2. This something that I been wanting to try with my students. This post and the link to the article gives me a good starting point to try this in my classroom. Have you tried doing this in your own classroom?
    T. Ward

  3. T Ward,


    I tried this 2 years ago with my middle school students, but I have not done it this year.



  4. Green screen indeed has a lot of applications. From home-made videos to blockbuster movies, such technology is being used. You have the option to setup your own studio or tap the services green screen professionals.