This article proposes an experimentation of an evaluation tool, the portfolio, in the formative evaluation of trainee teachers in the college cycle. A grid of criteria will allow, and the follow-up, and the visibility of the evolution of the training of these future teachers of the sciences of the life and the earth to the Regional Center of the Trades of Education and the Training (CRMEF) of Tangier in 2017. Thus, it is clear from the results obtained by using the portfolio as an evaluation instrument that can be adapted to different learning/teaching situations, that the trainees appear to be more involved in the training process. This instrument is able to stimulate their self-evaluation. They are thus made aware of the importance of evaluation and given responsibility for it thanks to the added value that the portfolio offers them. It allows trainees to become aware of their strengths, to value their work and also to measure the progress of their skills by rectifying and correcting their own mistakes.