Are you planning to stay in the Netherlands for a longer period? Then the cheapest option to travel is with an OV-chipkaart. The OV-chipkaart can be used on all forms of public transport and you do not need to think about getting individual tickets. You just pay by checking in and out with your OV-chipkaart. The price of your trip will be deducted from the credit on the card.
ISIC created the ISIC/OV-chipkaart, a custom made public transport card for international students. But why should you buy this card?
Buy the basic card for €15,- (including the ISIC card) and sign-up (optional) for services and discount created for international students for a monthly fee of €2,50 :