It is highly desirable for students to have some say about how their project is planned and conducted. If the project starts with the involvement of a partner, there may already be an agreement on the type of the project students will be involved in. If the partner only has something like tree planting in mind then there are fewer opportunities for students to be creative.
Where the partner only wants students involved in a very simple project such as tree planting, ask the partner to add something more to the project. Examples might be: