We've got a browser check page that will tell you whether Sumdog will work on your computer, and if it doesn't, what you need to do.
If your school uses filtering on its network, you may also need to whitelist "*.sumdog.com". The asterisk is important, as we use many subdomains that deliver different parts of the site. Your IT administrator will be able to help with this.
We also recommend that your web browser is as up-to-date as possible. If you are using an older version (for example, Internet Explorer version 9), Sumdog won't be able to work correctly.
If you're still experiencing technical issues, please let us know using this contact form.