INST TRAINING FLT LEAVING PHX OVERSHOOTS CLRED ALT.

Narrative

I DEPARTED PHX ARPT IN A TWIN ENG C414. I WAS THE PNF AND ACTING AS THE CFI; GIVING INST INSTRUCTION; TO A COMMERCIAL/MULTI/INST RATED PLT. WE DEPARTED VFR FROM RWY 26L (WITH A CLASS B DEP CLRNC) AND WERE SUBSEQUENTLY GIVEN A SWBOUND TURN AND A VFR CLB TO 8500 FT (RESTR TO 8500 FT). MY STUDENT WAS FLYING (UNDER THE HOOD) AND I WAS INTENTLY SCANNING FOR TFC. EVEN THOUGH I WAS TRYING TO KEEP AN EYE ON MY STUDENT; AND HIS TRACK AND ALT; I WAS VERY INTENT ON LOOKING FOR TFC IN THIS BUSY AIRSPACE. WHEN MY SCAN GOT BACK TO MY STUDENT AND HIS INSTS; I NOTICED THAT HE WAS APCHING 8800 FT AND HAD NOT STARTED TO LEVEL OFF. JUST AS I WAS ABOUT TO SAY SOMETHING; THE CTLR CALLED TO REMIND HIM OF THE 8500 FT RESTR; AND HE IMMEDIATELY LEVELED OFF. THE PRIMARY HUMAN FACTOR ELEMENT WAS MY PRIORITIZATION OF MY SCAN FOR OTHER TFC OVER MY ATTN TO MY STUDENT. IN RETROSPECT; I SHOULD PROBABLY HAVE REMINDED MY STUDENT OF THE IMPORTANCE (ESPECIALLY IN CLASS B AIRSPACE) OF THE ALT RESTR SOMEWHAT SOONER; BEFORE WE GOT CLOSE TO IT.