free tablet version of Stellarium for research sperimentation in astronomy education

Dear All,
I am an astronomy education research at the Milan-Bicocca University. Last scholar year, I began a research experience in a vocational school in Como about basic astronomy. I presented to students Stellarium and they appeared very enthusiastic of using it. They had the chance to use tablet at school, but school did not have the possibility to buy the Stellarium Application for all of them and teachers did not like to ask family to buy it. Since it is a research program, I would like to ask if there could be the possibility to have some free version to share with students (they are 25), they will be begin the new scholar year in two weeks.
Thanks in advance for your attention.
Kind regards,
Sabrina Rossi