What are the things that are prevented by minor ritual impurity?
There are five things prevented by minor ritual impurity:
1) To perform the prayer (wudu' is obligatory for all prayers, whether obligatory or sunna).
2) To make tawaf of (circumambulate) the Ka'ba.
3) To touch a Qur'an, or even only a part of it (even a single verse). It is even forbidden to touch it through a covering or with a stick.
4) To write out the Qur'an, even a single verse.
5) To carry a Qur'an, even if it is held by a strap or carried on a cushion or chair or piece of cloth.
As for teachers and students of the Qur'an, they are permitted to touch the Qur'an, and write it out on the tablet (lawha) while in a state of minor ritual impurity, even if there are menstruating women amongst them. If, however, they are in a state of major ritual impurity (janaba), then they may not touch the Qur'an until they have performed ghusl or tayammum (see Chapter 4 for the rulings on when it is permissible to do tayammum for major ritual impurity). Someone who is memorising or reviewing from a copy of the Qur'an is included in the category of student (but not if he is reciting it with the intention of worship).
Similarly, it is permitted for someone in a state of minor ritual impurity, even someone in a state of major ritual impurity (janaba) or a menstruating woman, to carry an amulet which contains Qur'an inside if that Qur'an is fully covered and dirt may not reach it
(NOTE: There is a difference of opinion about whether it is permitted to carry the entire Qur'an in an amulet. It is safer to take the position it is not permitted. The ruling for amulets also include things like coins which have Qur'an written on them and other such things).
It is also permitted for the one in a state of major ritual impurity to carry a Qur'an in his luggage when on a journey, if he intends to carry his luggage and is not merely carrying it as something in which to carry the Qur'an (In other words he was going to carry the luggage anyway and is just using it as a place to store his Qur'an).
As for carrying, touching and reading tafsir, there is no prohibition in carrying, touching and reading it for someone in a state of minor ritual impurity or even for someone in a state of major ritual impurity (janaba), because it is not considered to be a copy of the Qur'an
(NOTE: If less than half the text in a book is Qur'an, then it is permissible to carry that book without wudu'.)