What is the ruling on making models, such as worms and the like, at school?

It is impermissible to create statues of living beings. However, scholars have made exceptions for dolls used by pre-pubescent girls for play, to practice child-rearing, and to organize homes, as well as for items serving a benefit, such as educational tools in schools. Therefore, if these statues are needed by students for their learning and education, then there is no harm in them; otherwise, they remain subject to the original prohibition.