Early admission to kindergarten - Students enter kindergarten before they reach the minimum school entry age (which varies widely across states and districts).
Early admission to first grade - Students participating in this accelerative option attend first grade in their first year of school, either by skipping kindergarten entirely or by moving from kindergarten to first grade within the student’s first school year.
Grade-skipping (or whole-grade acceleration) - Students are placed in a grade level ahead of chronological age peers.
Continuous progress - Students engaging in this option are given new content as prior content is completed and mastered.
Self-paced instruction - In self-paced instruction, students proceed through learning and instructional activities at a self-selected pace.
Subject-matter acceleration/partial acceleration (Or content-based acceleration) - Students are placed in classes with older peers for a part of the day in one or more content areas.
Combined classes - Multiple grades are taught in the same classroom (i.e., fourth and fifth grades are combined into one class).
Curriculum compacting - The curriculum is adapted to include fewer introductory activities and less repetition. Adaptations should be made based on a pre-assessment of content knowledge.
https://www.dpi.nc.gov/students-families/enhanced-opportunities/north-carolina-governors-school
https://www.chccs.org/academics/gifted-education/gifteded/leap
https://www.proprofs.com/games/all/
https://www.davidsongifted.org/
https://www.extremeintellect.com/