Preparing for standardized tests like the SAT and AP exams can be enhanced through various free resources available online. Here are some recommendations for free SAT prep and AP prep for specific subjects:

Free SAT Prep Resources:

1. Khan Academy (SAT Practice):

   • Khan Academy SAT offers a comprehensive SAT prep program in partnership with the College Board. It includes practice questions, full-length practice tests, and personalized study plans.

2. College Board (Official SAT Practice):

   • Official SAT Practice by the College Board provides official practice tests, sample questions, and detailed answer explanations.

3. March2Success:

   • March2Success is a free online resource offering SAT prep materials, practice tests, and interactive lessons. It covers math, verbal, and writing skills.

4. 4Tests.com:

   • 4Tests.com provides free SAT practice tests and study materials to help you prepare for the different sections of the exam.

5. PrepFactory:

   • PrepFactory offers a user-friendly platform with SAT prep games, videos, and practice questions to make learning engaging.

Free AP Exam Prep Resources:

1. AP Classroom (College Board):

   • AP Classroom is a platform by the College Board that provides official practice questions, assessments, and resources for AP courses.

2. Khan Academy (AP Courses):

   • Khan Academy AP Courses offers free lessons, practice exercises, and resources for various AP courses, including AP Calculus, AP Chemistry, and AP Literature.

3. AP Review Booklets (AP Central):

   • AP Central offers free AP exam review booklets for various subjects. These booklets include sample questions, scoring guidelines, and exam details.

4. OpenStax:

   • OpenStax provides free, peer-reviewed, openly licensed textbooks. Check if there is a relevant textbook for your AP course.

5. YouTube Channels:

   • Many educators and organizations share AP exam review videos on YouTube. Channels like Bozeman Science and The Organic Chemistry Tutor offer content for AP Chemistry and other science subjects.

6. Coursera and edX:

   • Platforms like Coursera and edX offer free online courses from universities. While not specific to AP exams, they can provide additional learning resources.

Remember to verify the quality and accuracy of the resources you use. Official sources from the College Board are highly recommended for AP exam preparation. Additionally, practice exams and sample questions can be crucial for understanding the format and content of both SAT and AP exams.