In the histology practical, undergraduate students in medical school usually read the normal microstructures from glass or virtual slides and identify relationships between various cells and tissues of the human body to understand their corresponding functions. In a general medicine degree program in China, 32–36 classroom hours in the histology practical are instructed by teachers in late academic year 1 or year 2–3, depending on the curriculum.
In contrast to the USA and other countries, the medical students in China’s 5-year program who are enrolled from high school directly are required to complete 5.5–6.0 classroom hours for general arts courses and fundamental medical courses each class day during year 1. This means more skills training for them at the beginning of the medical curriculum, such as the aforementioned histology practical. Currently, histology has some new requirements. As modern technology consistently broadens the scope of human understanding, the explosive growth of biological and medical knowledge poses a new challenge: educators and learners must keep up with the relevance and depth of the comprehensive knowledge required for every subject course [1–2]. Students must also know how to apply and relate histology to corresponding courses, clinical cases, and medical research . The current integrated curriculum trend is decreasing teaching hours and emphasizing basic science courses in the pre-clinical years of medical education [4–5].
The updated learning requirements and new integrated design has brought about new learning objectives and lower teaching hours during the histology practical, which has led to better learning effectiveness than before. Therefore, it is essential that new approaches to teaching histology can fit the needs and workloads of medical students in China. Blended learning is one such method for facing the challenges of this unique era.
Blended learning is an educational strategy that combines traditional classroom activities with online activities in a flipped environment, where the responsibility of the teaching process is transferred to the students who have direct access to the content of the lessons before going to the physical classroom [6–9]. By providing students with online learning content in advance, flipped classroom learning increasingly engages learners. Blended learning has been extensively adopted and may become a new norm in higher education [10–11]. Two recent meta-analyses have also provided reasonable evidence of its effectiveness in improving learners’ learning skills and their scores [12–13].
The blended learning model contains six variations: flipped classroom, guided classroom time, integrated classroom time, capstone/independent learning, project-based and self-directed . And the flipped classroom model is the most common type of blended learning for undergraduate students. Various learning models exist under the blended learning umbrella, such as the four models of station rotation, classroom rotation, individual rotation, and the flipped classroom, which is the focus of this study . In addition to improving teaching quality, flipped classrooms are flexible enough to be easily adapted to a new learning model. One of the main challenges of a learning model revolution is the incompatibility between the old model and the new model; the flipped classroom solves this issue. The design of a flipped classroom model allows the implementation of various strategies in response to various course characteristics and the actual learning environment . It can also be readily implemented alongside traditional learning methods in an existing course .
Various studies on blended learning in medical education have shown similar results. In anatomy learning, students displayed a positive attitude toward a blended learning method in radiologic anatomy . The use of full-motion video from the anatomy dissection software really improved the experiences of the students in the dissection classes . With a flipped and blended learning approach, first-year students have found histology more manageable than before , while social interactions have also improved without compromising practical skills .
Some limitations of blended learning have been noted in previous studies. Regardless of how well blended learning is designed, factors such as emotional and affective issues might hinder its stability and flexibility  and challenge the self-regulatory abilities of learners [22–23]. While students are generally positive about a blended learning environment , a potential drawback of online near-peer anatomy teaching is that technological limitations and perceptions of online course instructors might lower student satisfaction .
In the blended learning of the histology practical, face-to-face learning is conducted in a virtual classroom, supported by conference software. With the development of modern educational technology, virtual microscopy, slides, and virtual classrooms have already seen extensive and positive application in the histology practice, such that some educators have already converted all courses involving light microscopy into a virtual microscopy format [26–28] as the acquisition of histological knowledge is independent of the microscopy types of the learning material. According to a survey  of histology learning from March 2020 to July 2020 during the COVID-19 pandemic in China, 50% of the responding schools (n = 39) showed a 50% increase in the use of virtual microscopy during online histology practical sessions; 48.7% (n = 38/78) implemented the online histology practical sessions in a flipped classroom (15%, n = 12) or via blended methods (33%, n = 26). The authors’ school was one of the schools that implemented a flipped virtual classroom that incorporated blended learning for histology during the pandemic.
The effectiveness of a physical classroom for blended learning and a virtual classroom for traditional learning in histology has been studied, but the effectiveness of a flipped classroom in blended learning is still not clear. In this study, we compared the effectiveness of blended learning between a flipped virtual classroom and a flipped physical classroom on students’ knowledge learning and conducted a satisfaction survey in the context of a blended learning experience within a flipped classroom model.