• Instead of selecting one cell, the entire column is selected in the main table.
• Pressing a number key on an empty column would start editing immediately.
  

Rationale

3 of 3 users had problems entering numbers in the table. When a cell is selected, pressing number keys would not enter numbers.

Taking the users directly to the editing table once they start entering numbers appeared to be a simple but not thorough solution. 4 of 4 users managed to complete the task. However, users expect the points to be plotted automatically.

• "OK" is removed from the screen. If the checkboxes are selected, the changes are reflected in the graph view.
  

Rationale

Users did not understand that "OK" is selectable, because it looked more like text. The user did not select "OK" and, and she was confused when she pressed "Graph" and saw an empty graph.

• The data points should be plotted automatically, as users expected. Also, include line of best fit in "Options" menu.

Rationale

With "OK" eliminated, 1 user did not know how to execute the intermediate setup screen after selecting the checkboxes. Pressing "Enter" would deselect checkbox while user expected it to execute.

Since there is no evidence that graphing the best fit line is a frequent task in Algebra 1, it is appropriate to move that to the "Options" menu, so the user does not have to go through the intermediate screen every time.

• Design 1 - Integrated Tables and Lists
  Keeping tables and lists together on the same screen but visually differentiate them, because users tended to go to "Table" directly for tasks that involved X and Y (for scatterplots).

• Design 2 - Separate lists from tables
  Having a separate button "Stats" or "Lists" on the calculator that display the lists horizontally, for the purpose of differentiating the lists from the table.
  

Rationale

To extend the current model for tables (for graphs and scatterplots) to include statistical lists, we investigated into two designs of handling lists.

Users entered the values for the dependent variable in the x column of the editing table. It appeared that the users were not aware of that, because the focus shifts from y1 to x in the editing table. Of the 2 users, one recovered the error and the other gave up.

• Tables and plots would be separated from statistical lists.
• The combined screen would include table of values to the left, and plot tables on the other side.

• Pressing on the "Lists" button would take the user to the list screen with summary statistics on the side, so users can see what statistics can be calculated.

Rationale

4/5 students

In design 1, users were confused between table of values and the lists. "x" and "y1" appeared to be strong cues for users to enter data.

Two students entered the values in the y1 column, and were confused because the entire column showed the same value (treating that as an equation).

One student wanted to enter values in the x column, and could not find a way to do so. Three users were hesitant in going over to L1.

3/5 students

Users were confused when moving to the right inserted another y column to the right. 2 users did not expect that, and dismissed it.

3/5 students

Users were confused when moving to the right inserted another y column to the right. Two users did not expect that, and dismissed it.

In design 2, all users went to "lists" after trying out a few buttons, if not immediately.

• All plots can be found in the same place.

• Once a user selects the option to enter a plot, the appropriate form would appear.
• For example, for a scatterplot, a two-dimensional table would appear.

Rationale

3/4 students

Users started to enter points in the y= screen.

4/5 students

Students wanted to find the "Pie chart" before filling in the data. 2 users gave up after trying several buttons and could not find it. They wanted to find the function first, then fill in the data, not the other way around.

2/2 teachers

Teachers saw an advantage for using y= screen for all plots. One teacher indicated that it is better to include all plots in the y= screen. Another teacher had mixed feelings, because "y= button tells me equations, but it doesn't tell me lists".

• Pressing "Enter" will take user to the plot/graph screen, and allow the user to use "Enter" to move down a column of cells, as users expected.

Rationale

3/5 students

Users pressed "Enter" in the y= screen after selecting a scatterplot, and expected the graph would show up, while it generated a prompt for another set of plot/graph. Since the y= screen prompts the user to "create" a graph, users may think that pressing "Enter" will create and take them to the graphs. ALso, one user said, "Pressing 'Enter' here [in the y= screen] goes down, but pressing 'Enter' in the list does not".

1/5 student

One user commented that he liked the highlighting of the different parts as he scrolls down the list.

2 of 5 users commented that summary screen is helpful.