Essentially in that clause the "werden" is missing. "verwendet" is the passive form and needs the additional "werden" to make the sentence complete.
You could rephrase the sentence to convert it to the active form, then you could omit "werden":
Schritte oder Techniken, die Studenten verwenden, um ihr eigenes Lernen zu fördern
This would be correct as well.
If you want to keep the passive form but omit the "werden" as well, then you could change the sentence to be a subordinate clause instead. That way you don't need a verb:
Schritte oder Techniken, von Studenten verwendet, um ihr eigenes Lernen zu fördern.