\begin{Schunk}
\begin{Sinput}
 library(openxlsx)
 fn <- file.path(ddir, "gradebook.xlsx")
 grades <- read.xlsx(fn, colNames = TRUE, check.names = TRUE)
 head(grades)
\end{Sinput}
\begin{Soutput}
    namelast namefirst     id hw1 hw2 hw3 mterm fin grade
1     Potter     Harry 453345   8   7   P    84  77     B
2    Granger  Hermoine 942832   7  NA   P   101 999    A+
3    Weasley       Ron 342234   9   8   F    78  88    B-
4     Malfoy     Draco 666666   8   4   P    66  85    C+
5      Brown  Lavender 234252   6   8   P    87  77     B
6 Longbottom   Neville 789897   5   9   F    81  79    B-
\end{Soutput}
\end{Schunk}
