Could you forward this technical issue to the correct department?   I like to keep a copy of the exercise available while I am actually doing the exercise so that I can refer back to the suggested vocabulary if necessary.  Sometimes this works, sometimes not.  In this exercise, I was not able to bring up two copies at the same time.  Even after starting the exercise, I was not able to bring up the page with the vocabulary while retaining my place in the exercise itself.  My position in the exercise would disappear and I would see the original page.  If I hit start on that page, it would jump to my position where I left off.  It was impossible to keep the original page and do the exercise simultaneously.  Thanks for looking into this.  Send me an email if you require additional details.