The equivSymbolic method checks that the value entered by a learner is mathematically equivalent to the Value the Author has set under Correct, even if they are in different forms.
Use equivSymbolic when using calculations or variables, where order or form is not important. equivSymbolic accepts decimals, fractions, variables, and percentages.
Examples using equivSymbolic
Example 1: Basic equivSymbolic
In this example, we have set the value 100 and chosen to Allow decimal marks (for a decimal point and thousands separator) to allow for things like 2,000 to be marked as correct.
In the image below, you can see how different learner answers would be marked.
Example 2: Variables
equivSymbolic can also be used with variables.
You can see in the example learner answers below that different forms of the correct answer are marked correct, as long as they equate to what you have set in Value. For each response in the example below the value was set to the same thing.
Example 3: Decimal rounding
Authors can specify a number of significant decimal places. In this example, Significant decimal places is set to 2. This way, learners will not need to enter all the digits after the decimal point for the response to be marked as correct.
In the example learner answers below you can see that many forms of representing a third were marked as correct. However, the answer that only specified to 1 decimal place (0.3) was marked as incorrect.
Example 4: Excluding possible correct responses
equivSymbolic is a very flexible method and is often used in conjunction with other methods. In some cases learners might need to give a response other than the one already specified in the question. Authors can set such exceptions by combining equivSymbolic and equivLiteral, then selecting Inverse result underneath equivLiteral. Now, any symbolically equivalent equation will be correct except for the value the author has set.
In the example below you can see that x² - 4 has been marked as incorrect.
Additional options for the equivSymbolic marking method
Significant decimal places
This option specifies the number of significant decimal places. The maximum value is 10.
Allow interval
This option must be enabled when the students are expected to insert interval notation in the response area, ie ‘[1, 4)’. Otherwise, the response will not validate correctly.
Ignore text
This refers to LaTeX text only, and when enabled will ignore any LaTeX text the student enters in the response area.
Compare sides
Used when comparing two constant equations, when both sides of an equation have not been fully specified, such as {{response}} + {{response}} = {{response}}. By default, expressions such as this will validate as isTrue. This means that as long as the expression is mathematically correct it will be correct, even if the value(s) entered is different to that specified in the validation area. However, enabling Compare Sides ensures that the response given is symbolically equal to the equation set in the validation area.
Treat 'e' as Euler's number
This option treats the variable 'e' as Euler's number. This overrides the default interpretation of 'e' as scientific notation.
Allow decimal marks
Authors can specify what separators learners can use. From the Thousand Separator drop-down menu, you can select dot, comma, and/or space. The Decimal Separator menu contains the option for either a dot or a comma.
Note: Allow decimal marks has to be selected for these options to show and that the specified thousand separators and decimal separator cannot be the same, e.g. both dot.
Treat all letters as variables
When this is enabled, the math engine will treat all letters as variables. This is useful in cases where you want to use letters as variables that the math engine may normally recognise as units of measurement.