Everyone has said a lot above, and I dare not say that all theories are wrong, but I think these things are a bit empty. LZ: I don't think the information you gave is enough to analyze the specific situation. First of all, I don't know if you are him/her. My mother or my father, I don't know whether my father or my mother has a great influence on my children. It depends on your daily observation (generally speaking, if it is a boy, I am friendly to my mother in primary school and junior high school, and I like to tell my mother from the heart that if my father is a more capable person, my child will want his approval). I think it's easy to disturb the child by just grasping his mentality.
We should pay attention to what children usually do besides studying and whether they are addicted to the internet, because if a child is addicted to the internet, his enthusiasm for learning is likely to decline. But if you are really addicted to the internet, you'd better not interfere too strongly, otherwise it will cause disgust. When chatting at ordinary times, it's best to inadvertently mention the disadvantages of being addicted to the internet, and it's best not to let the child feel that it's aimed at him. This may be more useful.
You can appropriately promise your child what to buy if you get good grades (usually you need to know what he likes, but it's hard to get it), and you should encourage him if you get good grades, but if he is the type of boasting his tail up to the sky, then it's best to knock the alarm bell after boasting, and don't get carried away. I think a little more praise is still positive for children's learning, because most parents like to say that their children are not good, so that children can always remember what is wrong with them, and maybe they will change, but forget what is good. Remember: if you don't boast, you will be forgotten, and as a result, there will be no advantages. If you constantly remind the advantages, the advantages will gradually accumulate.
Children are still young, and junior high school students are still in a stage of strong plasticity. You really don't have to worry too much. If you care more, you will have a chance to change. It is best to let your children make some good friends (good does not mean good grades, concrete analysis, it is best to complement each other's personalities and learn from each other's strengths in communication). As for the math problems you mentioned later, such as carelessness, simple mistakes and confusion, these are common problems of many children, especially boys (I have been there before and know them very well). Don't worry too much, as long as children can enjoy learning first, they will get better with their age. If your child has a dream and needs to be admitted to a university or even further study, these problems must be corrected when preparing for the college entrance examination. If not, these bad habits actually have little impact on personal life, so don't worry too much.
If I accidentally say too much, I'd better sum up the main points: encourage children more (but in a proper way). Generally speaking, father's encouragement is more effective. Find the key reason why children don't study hard and prescribe the right medicine. It is best for mothers to talk to their children more, because children are more willing to share their feelings with their mothers (especially boys of this age).