Hi Tetuan. I love the idea of your game, I'm sure there will be kids who would enjoy the challenge.
A few crits:
1 - You need to work on the presentation a little - it looks like a program/app from the 90's.
2 - I found that if you type too fast the game doesn't respond (I know it's aimed at kids but the game should still be able to cope with fast typing)
3 - Maybe add full screen ability