With the first login, students will be asked to enter a class number. From then on the device will remember this number, so they won't have to enter it again. Please make sure that cookies are enabled in the browser settings on the student's device. Cleaning cookies will reset the data, so students will have to enter the class number again.
You can also create a shortcut for your class page on each student device, so students can fast log into Happy Numbers.
Using Google Chrome on PC
Open Happynumbers.com in Google Chrome
Click the “I’m a Student” button and enter your 9-digit class number and click the “Go” button
Click the ••• icon in the right corner of the screen
Select “More tools”
Select “Create Shortcut…"
Edit the shortcut name and click “Create”. You've got a desktop Happy Numbers shortcut that points to Chrome
Using Safari on macOS
Open Happynumbers.com in Safari
Click the “I’m a Student” button and enter your 9-digit class number and click the “Go” button
Select the entire address in the address bar at the top of the browser
Click and drag the address onto the Mac OS X desktop and release the mouse button. A shortcut pointing to Happy Numbers class page is created on the desktop
You can check how to create a shortcut for your class page on other devices here.