First of all, as you are dealing with a Presentation task, ask your students to obtain the keywords which will help them to prepare their presentation. (they can find them in the first tab which is called INTRODUCTION). After they get the proper vocabulary, make them sure of getting the correct meaning of the word. That's why I recommend you the following online dictionary
Secondly, they MUST think of 5 national parks in colombia and make a research about them. Using the map in the proceduce tab to select them and if they need more information about them, surf the web link placed there.
Later on, in order to prepare the presentation, students should fill out the chart given in the procedure task to gather the relevant information. Also use comparatives and superlatives to compare one park to the others.
Finally, the student MUST prepare a fluent speech, speak slow and use the correct intonation. REMIND THEM TO ASK QUESTIONS TO THE AUDIENCE. Using the structures given in the introduction tab to astonish their audience and encourage them to participate and receive feedback.