  Cosmic rays are ubiquitous and readily available, making them a good teaching
tool for particle and astrophysics by young students. Tan-Q is an inclusive
outreach and educational project, providing students in Japanese junior-high or
high schools with research opportunities to join cosmic-ray and particle
physics. In the Tan-Q framework, the students in each school conduct their
research with help from mentors who are mainly undergraduate students.
Researchers are also extensively involved through regular Zoom meetings and
continuous communication on Slack. Some cases are inter-school, and some are
international. This paper presents one of the Tan-Q activities of joint
research between high schools in Japan and Argentina to observe cosmic-ray
muons using CosmicWatches. Our primary goal is to investigate the muon flux
differences due to the differences in circumstances like altitudes and
geomagnetic field strengths. Those involved learn not only particle physics but
also statistical data analysis methods.
