Research Methods: Three classes of students will be randomly chosen from the over 500 5th grades classes in a suburban district in Virginia, Prince William County. Students in this district are randomly assigned to classes with few exceptions. The classes will be chosen at random from a list of the 5th grade teachers in the county. As Prince William County is a suburb of the Washington, DC metropolitan area, students could potentially be from any of 89 of the known ethnicities represented in this county. Students will be both male and female. Classes may have slight different numbers of participants based on class size. However, class size is restricted to no more than 25 students and classes typically run between 23 and 25 students per class. Prince William County mandates the inclusion system at the elementary level which means that students with disabilities, students who are on the autism spectrum, who are in the normal functioning range, and students with gifts are all placed in the same classroom. This age range has been chosen because in this district, students with special services receive those services in the general classroom via an additional instructor such as a speech therapist, an occupational therapist, or via a gifted or special educator. Therefore, students of all abilities are placed together and do not receive any instruction outside of the classroom during the proposed science instruction. Thus, both random selection and random assignment are being used to heighten the validity of this study. All participants will be pretested using the Virginia Standard of Learning in Science and the Watson-Glaser Thinking Appraisal Short Forms (WGTCA-FS) was used to assess the subtopic skills of inference, recognition of assumptions, deductions, interpretation, and evaluation of arguments. Then the three classes will be taught the 5th grade Virginia Standards of Learning in science. The control group will be taught via traditional methods such as lecture, use of Power Point slides, and practice using worksheets and labs. The other two classes will be instructed using the problem-based approach in which students learn as they attempt to solve a problem. One of those classes will also use the reversed textbook. During the mid-term assessments, the students in all three classes will once again take the Virginia Standards of Learning in Science and the Watson-Glaser Thinking Appraisal Short Forms (WGTCA-FS) was used to assess the subtopic skills of inference, recognition of assumptions, deductions, interpretation, and evaluation of arguments. The constructs of this study are critical thinking and problem solving. They are operationalized through the assessments chosen. The problem solving construct is operationalized through direct instruction in the Problem Solving Strategy Steps (PSSS) for the test group with both the control and the test group being assessed on the Virginia Standards of Learning in Science assessment and the critical thinking construct is operationalized through the Watson-Glaser Thinking Appraisal Short Forms (WGTCA-FS) was used to assess the subtopic skills of inference, recognition of assumptions, deductions, interpretation, and evaluation of arguments. This design has clearly identified variables and constructs and uses a pre-test post-test method. However, the results could be stronger if each class was taught by the same instructor or multiple classes participated in each group. There could potentially be a mortality threat, but that is inevitable using random selection in the public school setting. This method was chosen for convenience and to ensure that all students received instruction in the required science standards. A after school program was considered, but ethically and financially it would not be feasible to arrange busing and ethically, it would not be right to offer a special program to some children. Further, if the after school program was used, the students would have to be voluntary participants. This would negate the random selection and random assignment strength