  Learning data storytelling involves a complex web of skills. Professional and
academic educational offerings typically focus on the computational literacies
required, but professionals in the field employ many non-technical methods;
sketching by hand on paper is a common practice. This paper introduces and
classifies a corpus of 101 data sketches produced by participants as part of a
guided learning activity in informal and formal settings. We manually code each
sketch against 12 metrics related to visual encodings, representations, and
story structure. We find evidence for preferential use of positional and
shape-based encodings, frequent use of symbolic and textual representations,
and a high prevalence of stories comparing subsets of data. These findings
contribute to our understanding of how learners sketch with data. This case
study can inform tool design for learners, and help create educational programs
that introduce novices to sketching practices used by experts.
