Why children make mistakes to write" b instead of "d"?

Im 19 and i still do that.

But i do b's and p's, which is more sound related and probably has to do with speech and hearing.

Your child looks more like a reading problem. Because b's and d's look similiar. Maybe you could figure out a way to write a b a little different than a d. or whatever way.

This is because they see letters as objects, like any other object in their environment. Other objects can be turned around and reversed and it does not change what the object is (think of a coffee cup, or a toy, sippy cup, or anything else), and in the early years of writing the kids haven't yet learned that for letters it makes a difference which way it is turned. This concept, where children use a rule they have learned and apply it to everything, even where it doesn't apply (the rule here being that an object is the same thing no matter which way it's facing) is called overgeneralization. It is completely normal, and the best thing you can do is to gently correct them and explain that when you turn the letter around it becomes a different letter (or for some letters it is simply backwards). Do not reprimand, as they grow they will naturally learn the correct way. not to worry!

When I was really young I had that same problem. To the best of my memory, I simply got the two confused. Sometimes if I double-guessed myself I would get thinking that I had mixed them up when really I hadn't and that only contributed to the confusion. It's just a matter of getting the hang of differentiating between two extremely similar characters. Nothing to worry about, just keep reminding them of the correct letters.

in my experience this generally corrects itself over time with practice and encouraging correction. It's kind of like right and left and getting shoes on the right foot, eventually they get it straight in their minds.

I suppose if you could come up with a simple, easy rhyme that might help.

Children learning to write often write lots of letters backwards (l, c, y, etc), they just haven't had enough practice yet.

When I was a kid I used to get confused too.I never confuse between B and D.I get only confused only with b and d.So I also made in my mind B=b.Like erase top portion of B gives b.Once you are sure about b then there is no confusion with d.

it's called "dyslexia", where the brain processes images backwards. It happens a lot when people learn to write a language. With some people, it's chronic, meaning they have trouble reading and writing their native language.

More to learn at Wikipedia.

http://en.wikipedia.org/wiki/Dyslexia