i have added action value Registration file
Electronic Montessori Learning
If on clicking the Register button , php code appears on the page , then most probably it has nothing to do with your code. Please check if you are directly double-clicking the html file for your testing . Please execute it by entering the localhost page address in the browser instead.
Eg : http://localhost/registration.html
Now the HTML should be able to execute the PHP code. And your folder containing html and php file should be in XAMPP->htdocs.