generates 15 million online participants in five days

Testing with Optimizely amplified their cause and boosted visitor engagement’s Founder Hadi Partovi is striving to ensure that every student in every school has the opportunity to learn to code.

Since founding the nonprofit in 2013, Hadi has focused on website optimization as a method garnering support and engaging more teachers and students in’s campaigns. He hired Roxanne Emadi in September to run testing.

The Hour of Code campaign aims to introduce millions of students across the country to computer science in just one hour. To say the campaign had a phenomenal turnout rate is an understatement. signed up 15 million users in five days—over half of which Hadi and Roxanne credit to A/B testing. Here’s how they did it.

Challenge: Engaging more teachers and students

Hadi and Roxanne wanted to improve the CTA and messaging on the Hour of Code registration pages to drive more sign-ups. They hypothesized that messaging that emphasized a sense of community around the movement would encourage greater participation.

Optimizing registrations

Text on original registration page for the Hour of Code campaign read — “Welcome to the 21st Century. Help us introduce 10 million students to computer science. All it takes is one Hour of Code.”

The original CTA read “Learn more”. Hadi and Roxanne tested the original messaging against new messaging that emphasized the community aspect. The variation CTA read “Join us”.


The variation messaging and call–to–action focused on the community aspects of the campaign.


The “community-focused” variation lead to a staggering 29% increase in signups for the Hour of Code. Hadi and Roxanne credit this experiment for generating about 8 million student sign-ups to the campaign.

Testing takeaways

Small changes can produce incredible results

You don’t have to revamp your entire website to achieve your conversion goals. Tweaking four short sentences and a call-to-action generated a huge win for Hadi and Roxanne—helping them reach 8 million additional students with their campaign.

A/B testing is an essential growth hacking tactic

Whether you work at non-profit, small business, or global enterprise, chances are you want to increase efficiency to achieve (and surpass) business goals. Website optimization with Optimizely is quick and easy – saving you time and helping you maximize your reach.

With Optimizely, we were not only able introduce nearly 1 in 4 U.S. students to computer science, but we were able to launch the fastest growing web service ever, which reached 15 million users in 5 days, faster than Facebook, Twitter, Instagram and Tumblr, combined.

Roxanne Emandi

Grassroots & Social Strategist,

Project Facts uses Web Experimentation

See the result at