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Formula Library

Evolution of Prototypes

 

Initial Design

 

Try prototype

To evaluate an expression:

User may select a formula, such as "Quadratic Formula" from the menu. Fill in all of the unknowns and then press "Enter" to see the answers.

Select "Quadratic Formula" from a menu of saved formulas.

The user can change the numbers around and press "Enter" to re-evaluate.

 

To solve an equation for 1 unknown:

User may select a formula, such as "Quadratic Formula" from the menu. Fill in all of the unknowns, select the unknown to be solved for, and then press "Enter" to see the answers.

User needs to move the cursor to select the unknown to be solved.

Once all of the numbers are correct, a checkmark will appear.

 

Iteration 1

Try Prototype

Design change: Separate solving and checking

  • If one field is left blank, then pressing "Enter" would solve for the missing variable. If all fields are entered, then pressing "Enter" would check if the equation is fulfilled.
  • The answer provided should be highlighted.
   

Rationale

2/3 students

Users were confused why "incorrect" was showing when they were not done entering. Users could not leave a blank in one of the fields and move the cursor down.

Design Change: Eliminate "P V N R T"

  • When the formula library is in checking mode, the bottom line would say "Enter Solves: n", or whatever variable the user is trying to solve for.
   

Rationale

3/3 students

Students did not understand what "P V N R T" at the bottom meant. Also, this tool is intended to solve equations with one unknown. The blank that is left empty would be the desired variable.

Design Change: "Clear" button should erase field

  • Pressing on the "Clear" button should erase the selected field, not taking the user back to the menu.
   

Rationale

2/3 students

Users could not backspace; pressing on "Clear" took them back to the menu.

 

Iteration 2

Try prototype

Design change: Disable text and show "?"

  • User is not allowed to enter text in any of the fields. The remaining variable to be solved would be denoted by a "?".
   

Rationale

1/2 students

1 of 2 users entered "n" for an unknown. There is no indication of what to do with the variable of interest.


Design change: Allow operations in fields

  • Instead of just numbers, the user would be able to enter simple arithmetic operations in the fields.
   

Rationale

2/3 students

Users did not pay attention to units. 1 student entered "273.15+25" in the temperature field.

 

3/3 students

Users entered the equation without multiplication symbol.