To prepare for a summer class in ordinary differential equations (ODEs), a solid review of linear algebra concepts is essential. Key topics to focus on include eigenvalues, diagonalization, and the Jordan canonical form, as these are crucial for understanding systems of differential equations. Familiarity with matrix operations and the matrix exponential is also beneficial. Basic concepts such as bases, linear transformations, determinants, vector spaces, and subspaces should be revisited, as they frequently appear in ODE contexts. While some students may not have formally covered canonical transformations, understanding the foundational elements of linear algebra will significantly aid in grasping the material in differential equations. Resources like Paul's Online Math Notes can provide valuable insights into the relationship between linear algebra and differential equations.