Three teacher researchers conducted this action research project to increase their 54 high school students' achievements in mathematics. The teacher researchers had noticed a trend of low scores on teacher-made chapter tests and non-completion of daily homework. Standardized tests showed that most students scored below average on the mathematics portion, and the number of students having to repeat mathematics courses had increased. The students' overall grades in mathematics have dropped, along with their attitudes towards mathematics learning. The project included 40 high school students enrolled in either Algebra 1-2 or Geometry classes, from August 27, 2008 through January 17, 2009. In each mathematics classes, there is a mixture of both freshmen and sophomores containing ten boys and ten girls. Both mathematics classes are collaborative classes where a regular education mathematics teacher and a special education teacher teach collaboratively. The teacher researchers planned three different interventions including incorporating multiple intelligence based lessons, offering positive reinforcement for homework, and involving the students in more regular group work. The teacher researchers started by having their students participate in a multiple intelligence survey and based their lessons on intelligences most prominent in their classes. To increase homework completion, the teacher researchers rewarded students who completed five consecutive assignments with a free homework pass. The group work took place during homework time in class. Students were divided into groups of four or five based on their ability level and worked as a team on homework and other activities. The teacher researchers gathered data using three different tools which included obtaining average test scores, average homework completion, and student surveys to understand how the collaborative setting affected their learning. They found that some of the interventions did not work as planned. For example, offering positive reinforcement to increase homework completion had a negative effect on the students. The decline in the average homework completion was 0.68% in one class and 6.22% in the other mathematics class. There were mixed results from both classes regarding the average test scores. Overall, the majority of the students felt that being in a collaborative setting helped to improve their learning in mathematics. (Twelve appendixes are included: (1) Collaborative Teaching Survey Pre and Post; (2) Strategy Survey; (3) Multiple Intelligence Online Survey; (4) Multiple Intelligence Lesson #1; (5) Parallel and Perpendicular lines Card Activity Worksheet; (6) Examples of Parallel and Perpendicular lines Cards; (7) Multiple Intelligence Lesson #2; (8) The Wave Activity; (9) Multiple Intelligence Lesson #3; (10) The Carousel Activity; (11) Multiple Intelligence Lesson #4; and (12) Triangle Inequality Game. (Contains 14 tables.) [M.A. in Teaching Leadership, Saint Xavier University.]