You will find a good orientation in the following article:
Guay, F., Morin, A. J., Litalien, D., Valois, P., & Vallerand, R. J. (2015). Application of exploratory structural equation modeling to evaluate the academic motivation scale. The Journal of Experimental Education, 83(1), 51-82.
One method that I used, many years ago, was to ask students to complete a ten-period timetable for their ideal school day. The rules were only that you could have no more than five periods of any subject.
Interesting to see how many periods are chosen for natural science.
But also, look at maths : few students will choose more than one period, but few will choose none at all, indicating that they may not enjoy it but they feel it's important.