# GEMS Education - Part 2
# Grades


TIP
When a model has very few simple fields with virtually no methods, it might be better to create an editable list view. As a result, this reduces unnecessary user clicks and lines of code.
# Schools

# Sessions




TIP
Odoo offers many error popups but we use ValidationError in constraints.
# Contacts

TIP
In practice, custom fields are added to res.users (User) model if they should affect access control on the users. Otherwise, the recommended model for custom fields is res.partner (Contact).
TIP
To display the age in years and months in the same line, you can use a combination of div and span elements with the class oe_inline. Alternatively, you can use an additional computed Char field for formatting.
WARNING
Ensure to add contacts module as a dependency in your manifest.