Long-term projects, which last a semester or longer, immerse students deeply in the topic of research.
Having conducted a 20-year meta-analysis of journal articles on project-based learning, Chen and Yang (2019, see below) argue that "project-based learning has a medium to large positive effect on students' academic achievement compared with traditional instruction."
Projects become even more effective when they can mobilize 4 C's

• Collaboration and the ability to work well with others
  
• Communication across contexts and audiences
  
• Critical thinking and the ability to solve complex problems
  
• Creativity and innovation

EVIDENCE:

Baprowska, A., & Nodzyńska, M. (2020). The Impact of Long-Term Education Projects on the Students' Conceptual Knowledge. Annales Universitatis Paedagogicae Cracoviensis. Studia ad Didacticam Biologiae Pertinentia, 310(X), 195-200.

Chen, C. H., & Yang, Y. C. (2019). Revisiting the effects of project-based learning on students' academic achievement: A meta-analysis investigating moderators. Educational Research Review, 26, 71-81.

Freeman, S., Eddy, S. L., McDonough, M., Smith, M. K., Okoroafor, N., Jordt, H., & Wenderoth, M. P. (2014). Active learning increases student performance in science, engineering, and mathematics. Proceedings of the national academy of sciences, 111(23), 8410-8415.

Gartner, T. B., Thomas, C. L., Geedey, K., Bjorgo-Thorne, K., Simmons, J. A., Shea, K. L., ... & Zimmermann, C. R. (2020). Strategies for Incorporating Long-Term, Distributed-Network Research Projects into the Undergraduate Curriculum: Lessons from the Ecological Research as Education Network's Decomposition Project. The American Biology Teacher, 82(3), 142-148.

Guo, P., Saab, N., Post, L. S., & Admiraal, W. (2020). A review of project-based learning in higher education: Student outcomes and measures. International Journal of Educational Research, 102, 101586.

Lee, J. S., Blackwell, S., Drake, J., & Moran, K. A. (2014). Taking a leap of faith: Redefining teaching and learning in higher education through project-based learning. Interdisciplinary Journal of Problem-Based Learning, 8(2), 2.

Lucas, N., & Goodman, F. R. (2015). Well-being, leadership, and positive organizational scholarship: A case study of project-based learning in higher education. Journal of Leadership Education, 14(4), 138-152.

Shin, M. H. (2018). Effects of Project-Based Learning on Students' Motivation and Self-Efficacy. English Teaching, 73(1), 95-114.

Vogler, J. S., Thompson, P., Davis, D. W., Mayfield, B. E., Finley, P. M., & Yasseri, D. (2018). The hard work of soft skills: augmenting the project-based learning experience with interdisciplinary teamwork. Instructional Science, 46(3), 457-488.