What does Slide Mean

Just started today and know nothing about singing.  What does it mean when the instructor says 1-5-1 or 1-5-1-8?  Does that mean do the lip trill for a count of 1, then 5, then 1?  Or does it mean going from softer to louder?

Hi, Mary!

Those numbers refer to scale degrees. In the key of C, for example, 1-5-1 would be C-G-C. In solfege, that's do-sol-do. You don't need to know any music theory in order to sing along, though! We always demonstrate what that sounds like for you, and play your pitches on the piano as well. Hope that helps!