GIS offers its students a strong and challenging mathematics curriculum that is reviewed and updated on a regular basis to keep up with the latest developments in math education. The Mathematics curriculum at GIS is based on the California Mathematics Academic Content Standards. The texts used for grades Kindergarten to Five are published by Scott Foresman-Addison Wesley, Millennium Edition. For grades Six and Seven, students use Passport to Mathematics Part 1 and Passport to Algebra and Geometry published by McDougal Littell, 1999 Edition. Eighth graders complete a first-year Algebra course and use the text Algebra published by Glencoe and adopted by the local Santa Clara public schools.

The Math curriculum is designed to ensure that the students will master all the skills needed to be successful in high school and it also incorporates numerous real life applications. During their years at GIS, students learn skills in the following strands of mathematics: number sense, geometry, measurement, statistics, algebra, probability and problem solving.