Interactive and Almost-animated Modules with Microsoft Excel Part II: Adding Controls for the Animation

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1 Interactive and Almost-animated Modules with Microsoft Excel Part II: Adding Controls for the Animation Thomas Mitchell, Associate Professor of Economics, Southern Illinois University Carbondale This paper written in two parts describes in step-by-step fashion how to create an interactive and almost-animated electronic resource for problems with graphs or charts, using Microsoft Excel. The source of the interactivity : we allow the student to choose the values of parameters in the problem. Each time the student varies the value of a variable or parameter in the problem, the student creates a different numerical problem or example. This means that the students have access to a virtually unlimited number of examples and practice problems. An additional value accrues more to the instructor. When students ask, What s the answer to Number 4 on the midterm?, the appropriate interactive Excel file is then a medium or environment in which students can work out the answers for themselves and on their own! The nature and usefulness of the interactive resource relies on several characteristics of a Microsoft Excel file. These characteristics include: the multiple-worksheet structure of Microsoft Excel files the ability to hide a worksheet where calculations and evaluations are done the ability to lock, or protect, workbook elements such as cells, charts or even entire worksheets. With access to a virtually limitless number of different examples and practice problems, the students have the flexibility to experiment with the what if? questions that can develop their intuition for the basic problem. Finally, once downloaded, the student need not be online to use the resource. There are no server-side elements and only Microsoft Excel is required to use the resource. Part I of the paper presents the basic structure of the Excel file and how to create it; it is available online at Part II of the paper, this part, shows how to add SpinButtons to a worksheet and make possible a user-moderated kind of animation. While the functionality of SpinButtons may be useful in a problem that is not represented with a chart or graph, we have found SpinButton controls to be especially helpful to students in recognizing and understanding the connections between numerical information that may be presented in a table (for example) and the graphical representation of the same information.

2 The Essential Structure of a File Although this is presented in Part I, it is worth pointing out or reviewing the essence of the Excel file structure that makes the interactivity possible. The essential structure is illustrated in the following figure. The image shows two panes. The two panes in the image are actually from different files as indicated in the title bars, but this is for illustrative purposes only; the image is intended to simultaneously depict two worksheets of a single file: the upper pane shows the worksheet that the student sees, named User_Data ; the lower pane shows the worksheet that eventually will be hidden from the student s view, named Hidden. On worksheet User_Data, there are two important cells, B2 and C2. The user may enter a number in cell B2. Cell C2 contains a message for the student-user, based on their entry in B2. The message in C2 is read from the hidden worksheet where the student s input is evaluated. On the hidden worksheet, there is another pair of important cells. In the figure above, cell B2 ( Hidden!B2 to completely identify the cell) simply reads the number the user has entered in cell B2 on worksheet User_Data. Cell C2 on the hidden sheet evaluates or processes the entry and displays a message. This message is read by, and displayed in, cell C2 on the visible sheet ( User_Data!C2 ). Page 2 of 15

3 With the above relationships and file structure, we need only to hide worksheet Hidden, protect it, then protect cell C2 of worksheet User_Data (and others like it) from accidental deletion or editing. To push the resulting interactive resource to another plane for teaching and learning and make it almost animated, or user animated, we want to add SpinButton controls that permit rapid changes in the value of a user specified parameter value. Toward that end, we need a file that s a bit more sophisticated than the file we developed in Part I. More particularly, we want a graph or chart to be tied to, or dependent upon, some values that the student provides. When the student changes a value with a SpinButton, we want to be able to see how the changing value in a table affects various elements depicted in the graph. Page 3 of 15

4 Adding Controls to a Worksheet In the file shown below, we see two numbers that specify a supply curve (albeit with a highly unusual shape to those who have taken any courses in economics). The Seller Cost of $30 determines the height of the horizontal portion of the red supply curve that connects the two vertical lines; the Number in Market of 37 determines the length of the horizontal portion of the supply curve. What are the objects below the two numbers? They are SpinButtons or spinner controls or just spinners. Page 4 of 15

5 By clicking on a SpinButton repeatedly or clicking a SpinButton and holding it down the student can generate motion in the chart. This creates a very visual connection between the numbers in the table and the elements of the graph. Creating this visual and hopefully mental connection is probably critical in any discipline that uses graphical representations of numerical data. So how do we put the SpinButtons on the worksheet? First we have to make sure the Control Toolbox is visible. From the View menu, choose Toolbars and Control Toolbox. Page 5 of 15

6 This adds the Control Toolbox to the workspace. To enter Design Mode, click the upper left button of the Control Toolbox. If the tool buttons on the toolbar are grayed out, then the worksheet is probably protected. Unprotect the worksheet before proceeding. Page 6 of 15

7 To insert a SpinButton, click the tool button for SpinButtons from the Control Toolbox. Pressing the toolbox button for a SpinButton changes the usual Excel cursor to a plussign (not visible in the image below, but note the depressed SpinButton button on the Control toolbar). Page 7 of 15

8 To create the first SpinButton, click-and-drag the pointer anywhere on the worksheet to initially set the dimensions of the SpinButton. Now click the Properties button on the Control Toolbox. Page 8 of 15

9 This brings up the Properties window. Page 9 of 15

10 Through the Properties window, we can change: the size of the SpinButton by changing the values of the Width and Height properties; the location on the worksheet by changing the values of the Left and Top properties. For the first SpinButton in the example file, Height = 15.75, Left = 229.5, Top = , and Width = size and place the SpinButton just beneath the Seller Cost number. In addition to changing the Height and Width properties in the Properties window, we can change the size directly by grabbing one of the handles (the little squares around the perimeter of the SpinButton control) and dragging it. In addition to changing the Left and Top properties in the Properties window, we can make large changes to the location or position of the SpinButton by dragging-anddropping the object directly on the worksheet; for small changes, the four arrow keys on the keyboard are especially helpful. Page 10 of 15

11 Another useful characteristic is the Orientation. The Orientation property may take one of three values. Orientation = 1 sets the orientation to horizontal, which is the orientation shown above. Orientation = 0 sets the SpinButton orientation to vertical, shown below (note that we have set the SpinButton to the left of the Seller Cost value). Orientation = 1 permits Excel to choose the orientation of the SpinButton that seems more appropriate given the values of Height and Width. With sizing and positioning settled, we now want to link the SpinButton to the value of a cell on the spreadsheet, establish bounds on the value and set the size of the change in the value from a single click on the control. Page 11 of 15

12 In the example file, if we select the cell containing the Seller Cost value of $30, we note that the cell is F10. (Note that placing the focus on the spreadsheet causes the Properties window to show the Properties of the worksheet instead of the SpinButton control!) Page 12 of 15

13 Clicking on the SpinButton again brings back that control s properties in the Properties window. Clicking on Linked Cell, pressing the Tab key and typing F10 then Return and we establish a link between the value of a cell on the spreadsheet and our SpinButton control. Page 13 of 15

14 For the sample file, we want the maximum allowable Seller Cost to be $49, the minimum allowable Seller Cost to be $1, and I want each click of the SpinButton to change the value by $1. Therefore, in the Properties window for SpinButton1, we set Max = 49, Min = 1, and leave SmallChange = 1. If we set up a second SpinButton and link it to the Number in Market value in cell G10, then we have the following. Now we are finished in Design Mode, so we (1) close the Properties window by clicking its upper-right corner X, (2) click the top-left button on the Control toolbar to Exit Design Mode, Page 14 of 15

15 and (3) close the Control Toolbox. The SpinButtons are part of the User_Data worksheet and we need to protect these (in addition to re-protecting the locked cells of the spreadsheet), so we have to choose Protection and Protect Sheet from the Tools menu. Save the file and now we re ready to watch some cool stuff: just start clicking away on the SpinButtons and watch the graph! Unfortunately, we cannot demonstrate the user-moderated animation in the static medium of this printed page ; to see how this works, go online for several examples. You can find the sample file developed here at the following location: ; its analog, a simple demand, is located at: ; their combination, a simple market, is located at: Two, more-sophisticated examples may be found at Page 15 of 15