AU - السعدي، محمد بن عبيد محمد AB - The study aims at tackling the weakness on using critical thinking of first year students through a study of a unit on 'Environmental Pollution', using the Problem-Centered Learning Strategy. This aim can be achieved by answering the following questions: 1) What is the effectiveness of teaching a unit on 'Environmental Pollution', using Problem-Centered Strategy on developing the following critical thinking skills: knowing hypotheses, explanation, inference and evaluation of arguments; of first year students at secondary level? 2) Is there any inseparable relationship between the general critical thinking and the critical thinking in Biology, of the first year students at secondary level? To answer the questions raised by the study, I have tested the following hypotheses: 1) Statistically, the average marks obtained by the students of the experimental group, which adopts the Problem-Centered Strategy, are higher than those obtained by the students of the control group, which adopts the Conventional Strategy in the post critical thinking checks in Biology. 2) Statistically, the average marks obtained by the students of the experimental group, which adopts the Problem-Centered Strategy, are higher than those obtained by students of the control group, which adopts the Conventional Strategy with the regard to the following critical thinking skills (knowing hypotheses, explanation, inference and evolution of arguments.3) There is no inseparable relationship between the marks obtained by the students of the experimental group in post general critical thinking tests and their marks in the critical thinking in Biology. The study adopts the descriptive which is used to study the effect of the neutral factor –the Problem-Centered Strategy- on the consequent variable –the Development of the critical thinking- of the first year students at secondary school level. I thus, have randomly chosen a group of first year students at secondary school in Bisha. The students are in the academic year 1426/1427 H. The total number of the sample group is 125 students, 60 of which, in the experimental group have studied the unit, using the Problem Centered Strategy. The remaining 65 students of the control group have studied the same unit using the Conventional Strategy. The critical thinking in Biology and the general critical thinking have been tested. (Published abstract) http://search.shamaa.org/abstract_en.gif OP - ص ص. 77-164 T1 - فعالیة تدریس وحدة التلوث البیئي باستراتیجیة التعلم المتمرکز حول المشكلة في تنمیة التفكیر الناقد لدى طلاب الصف الأول الثانوي بمحافظة بیشة [مقال] UL - http://search.shamaa.org/PDF/Articles/EGAsep/AsepNo35P4Y2013/asep_2013_n35-p4_077-164.pdf النص الكامل (PDF) 1 http://search.shamaa.org/fulltext.gif