On March 6th, 2018, the first tailor-made course on experimental methods in wastewater treatment was successfully conducted at IHE Delft. The one-day course has been given to a group of 60 participants from Holstebro Gymnasium from Denmark. The participants conducted batch activity tests to assess the activity of an activated sludge sample for the biological removal of organic matter, nitrogen and phosphorus. Under the guidance of our experienced experimenters Dr. Lopez Vazquez, Dr. Rubio Rincon and Mr. Berend Lolkema, the participants learned how to handle activated sludge samples and sequentially exposed it to different operating conditions using lab-scale sequencing batch reactors. Mr. Erik Bruun, biology lecturer of Holstebro Gymnasium and group leader, expressed his excitement and satisfaction by the results of this course and the importance of complementing and reinforcing the academic and technical skills of the participants.