How To Use A Green Screen For Online Teaching

How to Use a Green Screen in an Online Classroom


How Using a Green Screen can Transform Your Online ESL Classroom
and Elevate Interaction with Your Students

Many online ESL teachers use green screens in their lessons, and there are so many ways you can use a green screen to take your lessons to the next level. In fact, green screens have become so popular with online ESL teachers and students that some online ESL companies actually encourage their teachers to use them.

You will need to invest some time and money to get your green screen set up just right. The good news is that setting up a green screen environment is not too difficult, nor is it expensive.

What is a Green Screen?

A green screen is a backdrop made up of a single color (usually green, but sometimes blue). It is usually made of fabric such as muslin cloth, but can also be made from cardboard, canvas, and even green paint. For the purpose of this post, we will focus on the most common material used by online ESL teachers, which is fabric.

The green screen is used together with a technique called chroma-keying. The aim of this post isn’t to explain how chroma-keying works, but how you can use it in your online ESL classroom. So, we’ll give you this to-the-point explanation from MentalFloss author Nick Keppler:

Chroma-keying is the process of isolating a single color or brightness value in an electronic image and then making that value transparent in post-production, allowing another image or footage to be placed “beneath” the color that’s been blanked out. Although green is used so often that “green screen” and “chroma key” have become almost interchangeable, any color will work. Green is the go-to because it doesn’t match any natural skin tone or hair color, meaning no part of an actor will be edited out through chroma key.


Green screens are used in a variety of photo and video shooting scenarios; one of the more well-known uses of the green screen is the weather reporter on television. The example below shows how chroma-keying with a green screen works. The green color behind the person is isolated, then replaced with another image layer:

Why use a Green Screen in Your Online Classroom?

There are some obvious reasons for using a green screen in an online classroom:

  • It makes you look professional
  • You can use a variety of background images to elicit discussion and check comprehension
  • You can use your green screen with apps such as ManyCam to create more interaction in the classroom
  • You can change up your virtual background without redecorating your actual work space
  • Using a green screen effectively can help you get better ratings and thus, earn more classes

And some not-so-obvious advantages:

  • Your students can’t see your furniture, clothes, or personal items (or mess) in your home
  • Your family members or roommates can walk around the home without having to duck and crawl behind you while you teach online
  • You can travel or work from almost any location without your students knowing where you are (e.g., a hotel room)
As the old adage goes: A picture is worth a thousand words. Using background images can aid learning in place of teaching props for teaching and discussing topics such as geography, landmarks, landscapes, nature, food, and more. The list really does go on.

What Items Do You Need to Use a Green Screen?

A Computer with Fast CPU and Sufficient RAM

Modern Computer For Green Screen In Esl Classroom

You will need to invest in a few things, but before we get to these, it’s important to realize that software to use for chromakeying your green screen background during a live online ESL lesson can be incredibly demanding on your computer’s processor and memory, so you need to make sure you have a capable computer to handle the chromakeying processes while teaching online.

Our recommendation is to have a computer with at least the previous-to-current generation Intel i5 CPU running at 3GHz with no less than 4 cores, and at least 8GB of RAM.

Check out our recommended computers for online ESL teachers, all of which have the specs to perform well when using a green screen while teaching online.

How To Use A Green Screen To Teach Online Esl

Green screens range from very cheap, to very expensive. As an online ESL teacher, you don’t need an expensive studio-grade kit. Indeed, many online ESL teachers make do with fabric they buy from the local fabric store. The most important factors you need to consider when using a green screen for online teaching are:

  • Your green screen is free from creases and wrinkles. Creases and wrinkles in the fabric will create different shades of green that will make it difficult to chroma-key (isolate and replace) the green screen. You will also need to determine whether your green screen should be attached to a wall or hang over a frame.
  • Your green screen dimensions are large enough to cover the area behind you adequately. Your green screen should be both wide enough as well as high enough to cover the entire area picked up by your webcam. Dimension requirements will vary for each person based on their own height, work area, and whether you stand or sit while you teach online.

Check out our recommended green screens for online ESL teachers to help you decide which type of green screen is suitable for your online classroom setup.

Best Led Lamps For Online Esl Teachers

Many people who use green screens will tell you that your lighting setup is more important than the green screen. When using a green screen for online teaching, lights serve two purposes:

  • Illuminating the teacher
  • Illuminating the green screen

As you will discover when you set up your green screen in your work space, these two aspects will often conflict with each other. You might find that your face and body in the webcam view are well-lit, but there is some fuzziness around your head. On the other hand, you might find that your face and body in the webcam view are well-lit with no fuzziness around your head, but there is some fuzziness around the ends of the green screen. This fuzziness (often referred to as bleeding) is usually due to too much light on the green screen, causing the color to spill.

Both the amount of lighting as well as the color tones you use will play a role in striking the right balance. Different chroma-keying apps also handle the chroma-keying process differently. Ultimately, you will need to play around with your lighting setup until you get it just right.

Check out our recommended LED lights for online teaching to see which lighting options are best for your work space and green screen setup.

Chroma-Key Software

Green Screen Apps For Online Teaching

You will need an app that will chroma-key your green screen background. There are several free and paid apps available to accomplish this. What app you use will depend on your computer OS, as well as your specific needs. Some go beyond chroma-keying capabilities, like ManyCam Studio, which has an extensive set of features that enable you to show clip art, YouTube videos, add lower third text on your screen, wear a virtual mask, and much more.

The popular videoconferencing app Zoom, includes a virtual background feature that lets you skin your background with an image or video using a green screen, and if your computer’s CPU is powerful enough, you can skin it without a green screen. Zoom is an excellent app, but it’s only useful you’re using Zoom specifically for online teaching. If you use another platform, or if the online ESL company you work with has its own proprietary platform, you will need to use an app like ManyCam Studio, which creates a virtual webcam device on your computer that you can use with a green screen and more. Some teachers even use ManyCam and Zoom to access the additional features ManyCam offers while using Zoom.

Here is a list of apps that let you take advantage of your green screen:

ManyCam Studio ($59/year or $119 lifetime): ManyCam Studio is designed to give you a suite of screen effects while live streaming. Although ManyCam has a free version, to unlock the chroma-key feature, you will need to purchase ManyCam Studio (or ManyCam Premium). ManyCam Studio has an impressive feature set that can transform how you teach online and interact with your students. (Windows, macOS)

Screencast-o-matic ($20/year): This app has been designed primarily for video/screen recording and editing, so it is not as straightforward as ManyCam for live streaming (which is what a live online ESL class is). (Windows, macOS)

Open Broadcaster Software (Free): OBS is a free, open source software you can use to record and live stream your screen with a green screen background. Besides being free, OBS packs some really cool features, such as being able to set up multiple scenes, which means you can display images, videos, text, browser windows, and more, alongside yourself via your webcam. Free is hard to beat, but you’ll need to rely on the community and a public knowledge base to get support if you need help. Recommended for more advanced users. (Windows)

Navigating through the various app choices can be a bit of a task when starting out, so we recommend starting with ManyCam Studio, which is relatively easy to set up and straightforward to use.

Setting Up Your Green Screen to Teach Online Classes

Video Tutorial: Setting Up a Green Screen for an Online Classroom

In this short video, online ESL teacher and ESL Job Exchange content contributor Michael Wasserstein guides you through the important aspects of setting up a green screen for your online classroom. Michael is an award-winning online ESL teacher who uses a green screen extensively while teaching online.

Install and Run Your Chroma-Key App

The first step we recommend you take is to install and run your chroma-key app. Get familiar with the features of the app, so you can set up your green screen and lighting according to the functionality and recommended settings of the app. Again, for beginners, we recommend ManyCam Studio to get going quickly. Recent versions of ManyCam Studio let you skin your background without a green screen, though we still recommend using a green screen as it will give you a consistent color to chroma-key and thus, better results.

Measure the area behind you that your webcam captures. An easy way to determine the green screen size you need is to use a spare bedsheet in place of the green screen. Use some measuring tape to measure the dimensions of the bedsheet that come into the webcam view so that you can figure out the length and width of green screen fabric you will need to buy. You might need some help from a family member or friend to hold the bedsheet while you measure the area. A 6 x 9 foot muslin cloth green screen should be sufficient for most online ESL teachers.

You also need to decide if you will be attaching or hanging the green screen to the wall, or using a frame to hold your green screen in place. We recommend using a frame, as this will make it easier to move around the green screen as needed, and won’t damage your wall.

After you have purchased your green screen, make sure it is free of creases or wrinkles by ironing them out with an iron on low temperature. Once you’ve done that, you can attach it to the frame. Some green screens are set in a retractable frame, and if you are using one of these, then you can simply pull it open and lock into place.

Make sure your green screen is correctly positioned to fill up the area behind where you will be sitting or standing while teaching online. You will need to do this with your chroma-key app open on your computer so that you can view the area your webcam displays.

Now that you have your green screen in place, you need to determine is how bright your online teaching workspace is., and how many lights you need. If possible choose LED lights with different color temperature settings, so you can increase or decrease brightness in different spots of your work space.

You will need to position and adjust your lighting with you standing or sitting in front of your computer with the chroma-key app open to preview yourself and your webcam.

You’re not done with lighting just yet. Next, we need to find and insert an image layer to replace the green screen behind you to test your green screen and lighting set up with your app.

Choosing an Image to Chroma-key

Although you can use any image to replace the green in your green screen, we want to start with the most basic image that will enable us to test and tweak our green screen and lighting set up. For this, we can use a plain white image, because a white image is void of any color, and will reveal any issues with light spill/bleeding. Let’s see how to do this using ManyCam Studio:

Manycam Chroma Key
Image Credit: Visicom Media Inc.

Looking for a plain white image to insert into your chroma-key app? We’ve got you covered. Click the plain white image below to download it:

If you see any fuzziness or bleeding around your head or on the green screen itself, you will need to check for and iron out any creases/wrinkles in your green screen, and reposition your lighting. Using the white background will also help you figure out if you need to get add lights to your setup.

This image illustrates how the white background will replace the green screen. Notice the slight green spill around the hair, body, and hands.

Note: If you have long hair, we recommend tying it back to reduce the green spill around your head.

Finding Media to Use with Your Green Screen

As an online ESL teacher, you will constantly be on the hunt for media to use in your online classroom. A few excellent sites where royalty-free images can be found for free are:

These sites have a broad range of photos, illustrations, vectors, and videos to choose from, so you should have little difficulty spicing up your green screen images. Here are two images from Pixabay we put together to show you how we can replace the green screen layer:

Wrapping Up: Be Bold. Be Beautiful. Go Green.

Now that you have a good idea how to use a green screen in an online classroom, get started! It’s really not as difficult as you think, it’s very affordable, and the difference using a green screen will make to your online ESL lessons will be dramatic. It might take you a bit of time to adjust your green screen and lighting to get the ideal setup. It will take you a couple of days to get comfortable using the chroma-key software. But within a month (or less), you will find green screening a cinch, and you’ll begin to wonder how you ever taught online lessons without one.

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