Several of the textbooks on the approved list make extensive use of Sage.
A First Course in Linear Algebra
Rob Beezer
Applied Discrete Structures
Alan Doerr and Kenneth Levasseur
Sage for Undergraduates
Gregory Bard
Computational Mathematics with SageMath
Paul Zimmermann et al.
Understanding Linear Algebra
David Austin
The Ordinary Differential Equations Project
Tom Judson
Counting Rocks!
H. Adams, K. Emmrich, M. Gillespie, S. Golden, R. Pries
Abstract Algebra: Theory and Applications
Tom Judson
Number Theory: In Context and Interactive
Karl-Dieter Crisman
Elementary Number Theory: Primes, Congruences, and Secrets
William Stein