The loudest students in the classroom are not always the smartest. Many clever students like to think about things before they speak, making connections to prior knowledge, revising what they know and so on. Don't ever doubt your abilities just because you aren't making as much noise as other students in the classroom.
The students who finish first are not always the smartest in the class. Smart people know they need to find the right balance between working quickly and working carefully, as rushing can result in making careless or sillymistakes. You always need to ensure you read a question carefully and look at the key words so you know what you are being asked. Many students make mistakes because they explain whator howinstead ofwhy, for example. Smart people also generally check back over their work if they finish early. The best thing you can do is run your own race without looking at what other students are doing around you. In a running race, you don't have time to look at the students in the other lanes or turn your head to see how far ahead you are. Worrying about the speed of other students slows you down both on the race track and in the classroom.
Makingmistakes is expected. None of us is born knowing everything, so in the process of developing our knowledge and skills, we will make mistakes. Making mistakes is important because that is how we learn. The only time you might start worrying about mistakes is if you repeatedly fail to learn from them. If you aren't learning from them, ask for help and keep practising. Never give up and remember, we are all life-long learners. Your parents and teachers don't know everything ... they've just been on the learning journey longer than you have.