[AX7221]

In my opinion I would teach the blues shuffle I've copied and pasted below from another post, and the blues scale or minor pent. It was the first thing I improvised too and it's simple enough to enjoy it w/o thinking about too much stuff.

I have an mp3 of the riff here

Pentatonic Minor in G: (the convention I've used here is the strings and the frets that contain a scale tone on that string next to the string letter name)
e | 9 12
b | 9 12
g | 9 11
d | 9 11
a | 9 11
E | 9 12

Blues Scale in G: (minor pent with the blue note)
e | 9 12
b | 9 12
g | 9 11 12
d | 9 11
a | 9 10 11
E | 9 12

Here's a blues shuffle, each one is a measure in 4/4 time:

I
e|--------------------------
b|--------------------------
g|--------------------------
d|--------------------------
a|-2--2--4--4--2--2--4--4--
E|-0--0--0--0--0--0--0--0--

IV
e|--------------------------
b|--------------------------
g|--------------------------
d|-2--2--4--4--2--2--4--4--
a|-0--0--0--0--0--0--0--0--
E|--------------------------

V
e|--------------------------
b|--------------------------
g|--------------------------
d|-4--4--6--6--4--4--6--6--
a|-2--2--2--2--2--2--2--2--
E|--------------------------

Turnaround
e|------------------------------------------------
b|------------------------------------------------
g|------------------------------------------------
d|------------------------------------------------
a|-2--2--4--4--5--5--4--4--2--2--4--2--2-2-2-2--
E|-0--0--0--0--0--0--0--0--0--0--0--0--0-0-0-0--