— -- British teacher Sammy Roocroft wanted to teach her class of 9- to 11-year-old students the hard lessons about how private photos can go viral online.
Roocroft told “Good Morning America” that she asked her students to use Snapchat to take a photo of her holding a sign that read: “This is a ‘private’ Shapchat pic. Please share, like and comment where you are. Help me show my ‘primary’ class how private this pic really is!”
Roocroft, who teaches at Markland Hill Primary School in Heaton, England, then took a screen grab of the photo. She posted it to Facebook and Twitter and asked people to re-share the image and state their location.
Once she posted it, a friend shared it, then another and another. The growth was exponential -- leading to nearly 27,000 shares on Facebook alone from people in Australia, Denmark, Canada and many other countries around the world.
“A couple of the kids were using Snapchat and they had no idea that the images could be grabbed,” she told “GMA” via Skype. “They can't believe how fast this has spread and that this many people are seeing it.”
The whole premise of Snapchat is that the photos are deleted -- but users can capture a screen grab of sent images. To fight the oversharing, Snapchat now notifies users when a screen grab has been taken. However, some users have found a way around that, too.
Apps with names like SnapSpy and SnapKeep have cropped up that allow users to take screen grabs of Snapchat photos while circumventing the photo-sharing app's notification feature.
Underscoring the point of the experiment, some people online have already altered the photo Roocroft shared, adding harsh messages and even devil’s horns to Roocroft’s head.
"I've shared some of the negativity with my students, and I think that overall they really get the message," she said.