Hi Mary... I just went through two days of trial and error, but got a result I like. The following is an explanation of what I wanted to do, and the steps I took to get a result.
I wanted a Lightbox image gallery to open up in a popup window so that students voting on their favorite image could view the images in a separate window while voting in the Questionnaire activity from their Moodle page.
In the Description for the Questionnaire:
As part of the directions type "Click here to see: Images”
Highlight the word Images
Click on the Link icon
Click directly on the Popup tab (bypass the General tab)
Paste the URL for the activity (in this case the Lightbox image gallery)
Add x (600) and px (450) dimensions (x must be width, px height)
Click the box for Make window resizable