The LOFAR Data Processing School was hosted on 22-26 March 2021 online at ASTRON. The school provided a basic overview of the telescope and its science together with dedicated technical tutorials for data retrieval, pre-processing and visualisation.

Due to the COVID-19 pandemic, the school was shaped into an online event. The processing school counted more than 120 participants worldwide including 16 staff members and students from IANAO and TUS.  The attendees  of the school received first-hand experience of the processing pipelines of LOFAR, and learned the basics of data reduction in hands-on workshops. IANAO and TUS staff got familiar with requesting and downloading data; they were introduced to the data formats and to the various softwares for flagging and calibrating the data.

An online platform with pre-recorded sessions and real-time tutorials replaced the physical presence at ASTRON. The platform consisted in several Zoom rooms plus a Slack messaging and video platform where all the different lectures, demos and tutorials could be followed, giving the possibility to ask questions and share answers with the participants.

In addition to the Slack and Zoom platform, information of the Data School was shared with the participants via a dedicated website https://www.astron.nl/lofarschool2021/. Here the recordings of the lectures may also be found, allowing students to re-watch the material if necessary.