Catherine Szpindor, Chief Administrative Officer at House of Representatives, testified before the House Select Committee on the Modernization of Congress:

CAO training has evolved. It began with a few classrooms where you could learn WordPerfect and other technical skills. In 2017, the CAO launched a House focused professional development organization, the Congressional Staff Academy, that would better align with the needs of Members of Congress and their staff. This effort resulted in new state-of-the art classrooms, administrative systems, and most importantly, developed classes to address the needs of the House specific job profiles in Member and Committee offices…Since 2018, the Staff Academy has grown in its course offerings, and its attendance both in volume and efficiency. For example, in 2018 the Staff Academy had 1,601 students register for classes with a 28% attendance rate. In 2020 they had 8,548 students register for classes with a 64% attendance rate, and
this year they are on pace to exceed those numbers already serving 3,676 and maintaining a 64% attendance rate for students from Member and Committee offices. These numbers do not include required trainings such as Ethics, Cyber or Workplace Rights and Responsibilities, which combined means the Academy schedules, delivers, and tracks attendance for more than 40,000 individual seats in classes on an annual basis.