Mutation is the raw material of evolution. Understanding what evolution is, what its sources are, and how different forms of mutation operate is crucial for students. Instead of offering that information information crucial to the inquiry Explore Evolution purports to encourage the book misdefines and mischaracterizes mutation and ignores basic concepts in mutation.
After providing an inaccurate definition of mutation, and misdefining "structural mutation," the book then fails to describe the most common causes of mutation. Mutation can be caused by crossing-over during production of gametes, by errors in DNA replication, as well as the environmental factors which Explore Evolution describes as the sole causes of mutation. Mutations do not just occur in genes, the description in Explore Evolution notwithstanding.
The book errs in treating mutations as principally altering protein forms, rather than also considering the ways that mutations change the regulation of other genes, including protein-coding genes and other regulatory genes. The ways that genes are regulated is a key concept in modern biology, but these issues are simply ignored by the authors. The book focuses on antibiotic resistance, but even mangles that example, mischaracterizing the way antibiotic resistance evolves and the side-effects of mutations that generate such resistance.