Could you please help me express sentence 1. We have to consider the fact that groups of 10 students will be working on biodiversity in each school of the three schools separately and at the end they will compare their results.

1) Task organization and information distribution
The division of the various task will be ..... on the basis of the logical breakdown of the investigations
2) Experimental method
Students will be involved in the following investigating activities:
Systematic observation, measurement, and experiment
Formulation, testing, and modification of hypotheses

You're not including ALL the steps of the scientific method. Students need to start from the beginning, not somewhere in the middle of the process:

1. Ask a Question
2. Do Background Research
3. Construct a Hypothesis
4. Test Your Hypothesis by Doing an Experiment
5. Analyze Your Data and Draw a Conclusion
6. Communicate Your Results
http://www.sciencebuddies.org/science-fair-projects/project_scientific_method.shtml

Read through this, too.
http://sciencefairproject.virtualave.net/scientific_method.htm
Who will come up with the questions from which all investigations will stem?

On sentence 1, it would be helpful instead of the word logical, put something more specific. As in, what criteria does logic take? I would change it to "systematic", at least that implies some structure.

Certainly! To express sentence 1, you can say:

"In each of the three schools, groups of 10 students will be assigned to work on biodiversity separately. They will conduct their investigations and, at the end, compare their results."

Now, addressing the other points you mentioned:

2) Experimental method:
Students will engage in the following investigative activities:
- Systematic observation: Collecting data in an organized and structured manner to gain insights into biodiversity.
- Measurement: Taking precise measurements to quantify various aspects of biodiversity.
- Experimentation: Conducting controlled experiments to test hypotheses and examine cause-and-effect relationships.
- Formulation, testing, and modification of hypotheses: Creating educated guesses about biodiversity, then conducting experiments to verify or refine those hypotheses.

Please let me know if there's anything else I can assist you with!