Context

Happy Numbers is a freemium platform for teachers. To unlock full access, a new user needs to invite at least 3 colleagues via a referral program. The PM analyzed the funnel and found that many users opened the invite page but never completed it. User interviews revealed the main reason: teachers didn't know their colleagues' email addresses. To solve this, the team partnered with a third-party provider that supplied a database of teachers linked to their schools. This made it possible to replace manual email input with a pre-filled list of colleagues from the same school.

As-is screen

Key constraints:

Design the invite page with the following constraints:

• The partner database returns an average of 17 teachers per school
• Each row must show the teacher's name and email
• Fit as many teachers as possible on a single screen
• Keep the option to add emails manually
• Make it clear that at least 3 emails are required (by selection or manual input)
• Everything must fit on one screen — no scrolling
• Preserve the no-spam policy link and the "All rights reserved" footer

Success Metrics

• Referral completion rate — share of users who selected 3+ colleagues and sent invites.
• New email coverage — share of invited emails not already in the partner database. Relevant if growing the contact list is a goal.
• Invite volume — total emails sent per user. Useful if brand awareness is a priority.

Among the conditions, we need to add a table with pre-selected checkboxes for sending. I formulated the hypothesis:

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Pre-selected checkboxes (the full list of colleagues) will not reduce teachers' willingness to click 'Send invites'.

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