Answer: Double-blind experiment.
Explanation:
Double blind experiment is study in which participants and experiments do not have any idea about which participant or person will be going through treatment of experiment.This process in followed is experimentation to extract unbiased results.
According to the question,researcher is conducting double-blind experiment in which he does not know who will receive the treatment in experiment and neither students are aware about it.Also, their scores and names are not concealed.