Search Model - What am I doing wrong?

[eluser]jrutter[/eluser]
Here is my code, does everything look right? I have a form with a field name "search_terms" and I search on it and get: Message: Undefined variable: search_terms

Anyone have any tips?

Code:

<?php
class Search_model extends Model {

        var $search_terms;

        
    function Search_model()
    {
        parent::Model();
    }
    
    function search_parks()
    {
        
        $query = $this->db->query(
       "
         SELECT * FROM parks_tbl
         WHERE park_visible = 1
         AND   park_state LIKE '%". $search_terms ."%'
         OR    park_name      LIKE '%". $search_terms ."%'");
        
        return $query;

    }
    
}
?>