Scratch paper and pencils, or a whiteboard and markers.
Learners who are preparing for college admissions are advised to keep a portfolio (digital or on paper) of major assignments and 2-3 different types of problems, fully worked, per routine assignment; the materials of the student's choice should be available for this from the beginning of class. Examples include a Google Drive or Dropbox folder, LibreOffice software (Writer and Math), a binder and hole-punched printer paper or a hole puncher, etc. If you may apply to multiple colleges, consider that a digital portfolio is easier to duplicate, and can be printed if a physical copy is wanted.
For this class, learners can use GeoGebra exclusively as their graphing calculator. Learners with future plans involving taking exams like the SATs should consider getting and beginning to use a calculator approved for those exams as soon as possible.

In addition to the Outschool classroom, this class uses:
TeacherMade
GeoGebra Classroom

GeoGebra Classroom is a free educational website that uses open-source dynamic geometry software to help learners explore mathematical concepts. The website allows teachers to view and monitor learners' work in real time, and learners can also choose to create accounts that allow them to save and access their work at a later time. To use the site, learners will need to provide a name or nickname, which the teacher can use to identify their work in the teacher interface. This information is only used for the purpose of tracking progress and is not shared with any third parties. Learners are welcome to use a pseudonym or nickname if they prefer to maintain their privacy.
TeacherMade is an educational website designed for use in schools. It provides learners with access to a variety of worksheets, tutorials, and practice problems to help them learn and reinforce important concepts. To use the site, learners can either use their real names or choose to sign in with a pseudonym or nickname for added privacy. The website is designed to be safe and secure, and all learner information is kept confidential and only used for the purposes of tracking progress and providing personalized learning experiences.