Your teacher's child should be about the same age as you, because you are about the same age, so what you like, she will also like almost the same thing, girls like similar things. Nowadays, people born in the 80s and 90s are very eclectic, and they like creative, personalized, and thoughtful gifts, so you should know what to give.
Generally, girls carry a beautiful small mirror with them to touch up their makeup at any time. The image of a girl is very important, so I also suggest that you give your teacher's child a makeup mirror, which should be specially made, such as the kind with mirror engraving. It is not only convenient to carry, but also very practical. It is a good gift recommendation!
You can also give other accessories, such as name necklaces, constellation necklaces, health bracelets, agate bracelets, personalized tags, etc. Anyway, they are all liked by girls, and they are personalized and customized, which is quite good!
If you don't want to give jewelry, you can also give chocolate, luminous lamps, sun jars and other gifts. Sun jars can collect sunlight during the day and automatically glow at night. This is the dream of every girl, so these gifts are also good. In any case, as long as you cater to the teacher's preferences and give whatever the teacher's children like, you won't go wrong.