The teacher motivates the students to work on this topic by showing advertisements referring to “Chitosan – Fat Magnet!”


During this phase the teacher explores together with the students the following questions and introduces the students to the new content (chemistry of chitosan, poly-saccharide) and (if necessary) to the strategies and tools needed to work on these questions (internet browser, search engine, mind manager)

  • Is there any useful information about chitosan as fat blocker on the web?
  • What is Chitosan?
  • Which properties characterize Chitosan?
  • How does Chitosan interact with fat?
  • Where do we find Chitosan in nature?
  • How can we produce Chitosan?

    The teacher leaves many open questions but has provided the students during the first phase (as a kind of advance organizer) with some content knowledge and adequate learning strategies.

    During this phase the students work in small groups on the open questions. They try to find information (mainly from the internet) about chitosan as fat magnet, about the structure, production and properties of chitosan. They had to identify relevant information, evaluate and understand the content, relate it to previous knowledge and store it in a structured way in mind maps.


    They carry out own experiments e.g. to produce chitosan from shrimp (crab) shells and try to find out how it reacts with fat and also with other substances (see students’ activities and experiments) to find out more about chitosan’s properties.

    Now they start to answer the questions of the starting phase. The students have learnt how to produce chitosan from shrimp shells, they have learnt how chitosan reacts with fat or fatty acids. They have read some papers on chitosan as fat blocker giving differing information. Does it work or does it not work? They reflect their findings, discuss them with their classmates and prepare a public presentation with posters, experiments and Powerpoints.


    The overall question is not only about its chemical functioning but also about should we use this substance ourselves or recommend it to friends to control weight? This question leads beyond pure science, includes general problems with drugs/ pharmaceuticals and balanced diets and healthy way of living.


    After having discussed the results and problems also extending the chemical content students are asked to make personal decisions whether they would use this drug for supporting the process of reducing weight or whether they would recommend it to friends. They gather arguments pro and contra chitosan and defend their decision.

    Pro Con
    Easy to administer There are no serious studies to prove its effectiveness
    Life quality:  You don‘t need to miss fat in your food

    It works only in acidic environment, but the intestine is basic

    You avoid quite easily unhealthy overweight Fat soluble medications can be compromised in its effectiveness (oral contraceptiva, estrogen)
    Creative method of using waste

    The missing fat will also hinder vitamines from entering the metabolismExperiment: see classroom material

    Producing more shrimps in Asia will destroy mangrove woods
    It‘s much more healthy to eat balanced food and do exercises