  Quantum information science is a rapidly growing interdisciplinary field that
is attracting the attention of academics and industry experts alike. It
requires talent from a wide variety of traditional fields, including physics,
engineering, chemistry, and computer science, to name a few. To prepare
students for such opportunities, it is important to give them a strong
foundation in the basics of quantum information science, in which quantum
computing plays a central role. In this study, we discuss the development,
validation, and evaluation of a tutorial on the Bloch sphere, a useful visual
tool for developing intuition about single quantum bits (qubits), which are the
basic building block of any quantum computer. Students' understanding was
evaluated after they received traditional lecture-based instruction on the
requisite topics, and again after engaging with the tutorial. We observe,
analyze, and discuss their improvement in performance on concepts covered in
the tutorial.
