I'm old fashioned and I still have my song books. When I was jamming, I always took them and set them up on a music stand. No one seemed to take offense because I was reading words from a book.

As far as screens go, I doubt I'd be able to actually see the words from a hand-held device.

Geez, this old school guy wouldn’t have a clue how to use your tool bluegrass98.com. I’d be writing them out long hand ,,,remember that?… lol

I like using a jam to strengthen my ear playing.
My favorite jam challenge is being offered a break to a first-time hearing of a song.

I follow the "look at the guitar players' right hands, lay back if you don't know the song" most of the time.

IF the jam in the OP is an "instructional" jam, then I feel printed copies would be good. 

IF it's a conventional (?) jam, then just carry on carrying on, I suppose.

Earl, when I was teaching and kids would confuse (?)  right/left I'd often point it out with: "... Your other right* hand."

* or left, as the case may be.  

I use a 10" android tablet and Songbook Pro (logo is 2 not3s in b&w).

Advantages I have:
* I can search a song and have it displayed in about 15 seconds. Then I sit and wait a minute or more for the binder people to find the song. Sometimes they got it only one month ago and have not alphabetized it yet

* I have 2000 songs already downloaded

* I can transpose the song to another key in about 5 Seconds

* I never forget the lyrics to the third verse and usually I can tell you who wrote the song.

* I'm ready to tell the entire group what the chord progression is without jumbling it up.

* I can feed the 3rd and 4th verses, at least the first few words to the person that called the song when they forget.

* I can create setlists for multiple gigs and keep them straight. Also handy for maintaining a list of the current songs I'm learning or practicing.

Of course, I have the greatest admiration for people who can remember 200 to 300 songs and all their words. I admire people who can improvise breaks better than me. I admire people who can pick up the chord progression faster than me.

I admire those people but I am not those people. I am myself and my little tablet helps me be the best version of myself.

I recommend to most people to go without any reference materials. It's a good opportunity to learn to hear and feel chord changes.

If I'm learning a new song I don't consider it learned until the lyrics are memorized. The bonus is once it's memorized it's performance ready and can be played on stage or on the fly where a book wouldn't be available or appropriate.