A little more detail for those who will undoubtedly be searching in the future (like me right now).
To get the Glitch url you want for the solution field on lessons:
- in the left hand column click on the down arrow next to SHARE (next to the little avatar icon).
- Under Link to Glitch there are three tabs. Click on the middle tab Live App
- Next click on COPY next to the URL shown.
here is a good visual of the how to:
I had trouble with this also until I went and played around with it (Hmm lets see what this does…).