Start from the most basic explanation of databases. The most generic database will contain only one table. This is very simple and information can be retrieved using the scroll bar or sorting functions.
A relational database contains more than one table. With more tables, the amount of information is multiplied and it becomes hard to locate certain things or to view certain groups of information.
The key to a relational database is to relate certain information such as names, crops, and area so that you can view all related information which pertains to each category.
A finished relational database can be used to retrieve all the necessary information regarding one category using a single query.
Try and keep another computer and perform the tasks in the presentation.
Perform example queries to show how it is a hassle to do it every time.