Steps:
1. Open a tab "Teachers"
2. Click on the button "New""
3. Enter first name in the field "First name"
4. Enter last name in the field "Last name"
Expected results:
1. Only numbers and letters can be used
2. It is not possible to create a new teacher entering special symbols in fields "First name" and "Last name"
Actual results:
1. Special symbols in fields "First name" and "Last name" can be used
2. It is possible to create a new teacher entering special symbols in fields "First name" and "Last name"