ГДЕ или КУДА?
Both of these words translated as "where" into English but we use them in different situations.
ГДЕ?
Used when we talk about location.
- Где ты работаешь? Where do you work?
- Я работаю в школе. I work at a school.
Please pay attention that in this case we use the prepositional case.
Школа - (где?) в школе.
КУДА?
Used when we talk about direction, there is movement somewhere. Often used with verbs of motion.
Куда ты идёшь? Where are you going?
Я иду в школу. I'm going to school. (I'm on my way to school right now, not there yet)
Here we use accusative case.
Школа -(куда?) в школу
If you want to practice a little, answer the questions
Где вы любите отдыхать?
Куда вы ходили в выходные?