21
Jan 23

## Excel for mass education

### Problem statement

The Covid with its lockdowns has posed a difficult question: how do you teach online and preclude cheating by students? How do you do that efficiently with a large number of students and without lowering the teaching standards? I think the answer depends on what you teach. Using Excel made my course very attractive because many students adore learning Excel functions.

### Suggested solution

Last year I taught Financial Econometrics. The topic was Portfolio Optimization using the Sharpe ratio. The idea was to give the students Excel files with individual data sizes so that they have to do the calculations themselves. Those who tried to obtain a file from another student and send it to me under their own names were easily identified. I punished both the giver and receiver of the file. Some steps for assignment preparation and report checking may be very time consuming if you don’t automate them. In the following list, the starred steps are the ones that may take a lot of time with large groups of students.

Step 1. I download data for several stocks from Yahoo Finance and put them in one Excel file where I have the students’ list (Video 1).

Step 2. For each student I randomly choose the sample size for the chunk of data to be selected from the data I downloaded. The students are required to use the whole sample in their calculations.

Step 3*. For creating individual student files with assignments, I use a Visual Basic macro. It reads a student name, his or her sample size, creates an Excel file, pastes there the appropriate sample and saves the file under that student’s name (Video 2).

Step 4*. In Gmail I prepare messages with individual Excel files. Gmail has an option for scheduling emails (Video 3). Outlook.com also has this feature but it requires too many clicks.

Step 5. The test is administered using MS Teams. In the beginning of the test, I give the necessary oral instructions and post the assignment description (which is common for all students). The emails are scheduled to be sent 10 minutes after the session start. The time for the test is just enough to do calculations in Excel. I cannot control how the students do it nor can I see if they share screens to help each other. But I know that the task is difficult enough, so one needs to be familiar with the material in order to accomplish the task, even when one sees on the screen how somebody else is doing it.

Step 6*. Upon completion of the test, the students email me their files. The messages arrival times are recorded by Gmail. I have to check the files and post the grades (video 4).

### Skills to test

Portfolio Optimization involves the following steps.

a) For each stock one has to find daily rates of return.

b) Using arbitrary initial portfolio shares, the daily rates of return on the portfolio are calculated. I require the students to use matrix multiplication for this, which makes checking their work easier.

c) The daily rates of return on the portfolio are used to find the average return, standard deviation and Sharpe ratio for the portfolio. The fact that after all these calculations the students have to obtain a single number also simplifies verification.

d) Finally, the students have to optimize the portfolio shares using the Solver add-in.

The list above is just an example. The task can be expanded to check the knowledge of other elements of matrix algebra, Econometrics and/or Finance. In one of my assignments, I required my students to run a multiple regression. The Excel add-in called Data Analysis allows one to do that easily but my students were required to do everything using the matrix expression for the OLS estimator and also to report the results using Excel string functions.

To make my job easier, I partially or completely automate time-consuming operations. Arguably, everything can be completely automated using Power Automate promoted by Microsoft. Except for the macro, my home-made solutions are simpler.

### Detailed explanations

How to make Gmail your mailto protocol handler

Video 1. Initial file

Video 2. Creating Excel individual files

Video 3. Scheduling emails

Video 4. How to quickly check students work

Macro for creating files

Sub CreateDataFiles()
'
' This needs a file with student names (column A), block sizes (column C)
' and data to choose data blocks from (columns F through M). All on sheet "block finec"
' It creates files with student names and individual data blocks
' If necessary, change edit whatever you want
' Also can change the range address. R1C5 - upper left corner of the data
' "R" & Size & "C13" - lower right corner of the data
' Size is read off column C

' First select the cells with block sizes and then run the macro

' Files will be created and saved with student names
' Keyboard Shortcut: Ctrl+i
'
Application.ScreenUpdating = False
For Each cell In Selection.Cells

Size = cell.Value
Name = cell.Offset(0, -2).Value

Application.Goto Reference:="R1C5:R" & Size & "C13"
Application.CutCopyMode = False
Selection.Copy
ActiveSheet.Paste
ChDir "C:\Users\Student files"
ActiveWorkbook.SaveAs Filename:= _
"C:\Users\Student files\" & Name & ".xlsx", _
FileFormat:=xlOpenXMLWorkbook, CreateBackup:=False
ActiveWorkbook.Close

Workbooks("Stat 2 Spring 2022 list with emails.xlsm").Activate

Next
End Sub