You may want to create one portfolio for all your partnered schools and mail it around to each school. School, City, State. Description of the moon. Description of other stars. Description of weather conditions.
Scientists work in a very methodical fashion.
Maintaining accurate records of observations and measurements is a key component in this systematic method. Every student should keep accurate chronological record, possibly in a scientific investigations journal or science lab book, of everything which they do in the investigation. These notes should be placed within the student's portfolio for assessment purposes. Writings and drawings summarizing what the student has observed should be included within the student's portfolio. An analysis or comparison to other students' viewpoints might also be included in the portfolio.