This research was conducted to study the effectiveness of the supplementary instructional materials in Mathematics for the first year high school students in four selected schools in the Division of Caloocan. From the identified weaknesses, a set of supplementary instructional materials in Mathematics was proposed.

The research investigation using the descriptive and experimental research method utilized 482 first year high school students as subjects, 40 mathematics teachers and four school administrators as respondents.

The specific problems raised in the study are the following:

1. What are the identified weaknesses among first year high school students in Mathematics based from the Summative Test?

2. What supplementary instructional materials may be developed?

3. How acceptable is the supplementary materials to the

mathematics teachers and school administrators to:

3.1 Objectives;

3.2 Contents;

3.3 Language and Style; and

3.4 Evaluation

4. How do the students perform in the Pre-test with the use of the supplementary materials? How significant, if any in the relationships between the results of the Pre-test and Post-test?