Evaluation Modes for Math Questions

For many question types in WebAssign®, such as Multiple-Choice or pencilPad, the question mode you select has immediately visible effects on the question you are creating. When you create questions that evaluate mathematical expressions, however, the question mode you select affects what kind of responses your students can enter and how your students' responses are evaluated, but has no corresponding visual effect.

Note: If your students should respond with a numerical answer and not a mathematical expression, see Create Integer or Decimal Number Questions.

Before creating a question that asks your students to enter a mathematical expression or equation, determine how that expression should be evaluated.

Symbolic Mode

Symbolic questions evaluate your students' responses symbolically by substituting a series of values for the variables in the response and in the key. If the response and the key are equal for all tested values, then the response is accepted as correct.

This evaluation behavior provides reliable scoring of responses and can accept any form of a mathematical expression that is equivalent to the key. However, it cannot evaluate responses that are equations, and it cannot evaluate whether responses are in a particular form, such as a completely factored expression.

Algebraic Mode using Mathematica®

Algebraic questions evaluate your students' responses algebraically using Mathematica, in much the same way you would solve an equation.

Note:

Algebraic mode is a much more powerful method for evaluating your students' responses, but specifying your key in Algebraic mode can sometimes be more complicated than with Symbolic mode. Additionally, you cannot by default accept any mathematically equivalent response using Algebraic mode; you must therefore make sure that your students understand what form of response is needed.

Choosing a Mode to use Based on Selected Criteria

Refer to the following table to help you decide which mode to use. 

Best Practice: If you can use either Symbolic mode or Algebraic mode, use Symbolic mode.

Criterion / Example

Symbolic Mode

Algebraic Mode using Mathematica

Accept any response that is equivalent to the key

yes
no

Allow your students to type commas in large numbers

yes
no

The answer is a single mathematical expression that is not an equation.

Solve for x:

2x+y2-6=0
yes
yes

The answer is a finite list of set members.

List the first three natural numbers.

yes
yes

The answer is any member of a set.

List any multiple of both 2 and 3.

no
yes

The answer is a single ordered pair.

What are the coordinates of the center of the circle defined by the following equation:

x+32+y-42=25
yes
yes

The answer is two or more ordered pairs.

List the coordinates of the first five data points shown on the graph.

yes
no

The answer is a vector.

Find a vector perpendicular to ‹1,2›.

no
yes

The answer is an equation.

What is the equation for a circle with center (x,y) and radius r?

no
yes

Only a particular form of the answer is correct.

Factor the expression:

x2-x-12
no
yes

Key can specify multiple correct answers.

no
yes

Key can perform complex evaluation functions for you, such as factoring polynomials or computing derivatives.

no
yes