Tipo de pregunta conjunto numérico variable

Un Tipo de Pregunta Calculada Numérica con evaluación de expresión y variable. Todos los valores son precalculados, a pesar de que una pregunta pueda tener varias variantes con diferentes valores de variables para cada variante.

Características

Las preguntas de conjunto numérico variable son similaes al Tipo de Pregunta Calculada Numérica, pero están limitadas a un ‘conjunto’ de valores pre-especificados. Como tales, las preguntas de conjunto numérico variable son más seguras para usar, ya que se pueden probar todas las variaciones posibles antes de que la pregunta sea liberada a los estudiantes.

Las preguntas de conjunto numérico variable ofrecen un rango de mejoras con respecto al Tipo de Pregunta Numérica . Por ejemplo, al momento del examen hay una rutina de validación que asegura que el estudiante haya escrito un número válido y se proporciona un mensaje de error si hubiera un error en la respuesta introducida.

Las preguntas de conjunto numérico variable usan cálculos y valores numéricos que son realizados al momento de la ejecución del examen, siguiendo reglas que están puestas dentro de la pregunta.

Descarga

Desde el Moodle Plugins database

Nombre y texto de la pregunta, puntaje y retroalimentación general

Variables that are selected or calculated by the computer are included in text fields by placing the names of the variables within double square brackets e.g. [[a]]. The formatting of the numbers may be controlled using sprinf() style controls (http://php.net/ manual/ en/ function.sprintf.php [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] ). For example [[a,.3e]] will display the value of a in scientific notation with 3 decimal places. The most usual formatting choices are ‘d’ for integers, ‘f’ for floating point or ‘e’ for scientific notation.

The random number generator can be seeded

Sometimes it is desirable to base a sequence of questions on the same set of numbers. To do this use the same string e.g. ‘mystring’ as the ‘seed for randomisation’ in each question in the sequence.

Please note that this then generates the same set of numbers across a sequence of questions for a student but different students get different sets of numbers. Interested readers may wish to know that behind the scenes the random number seed that is used combines the seed provided by the author, the students PI and the students attempt number.

Archivo:Figura 5 16.jpg Two pre-specified sets of values and one calculated set

The formula for all calculations should start with a variable name followed by an equals (=) sign and may use common mathematical operators +, -, *, /, brackets, (, ) and other variables defined within the question.

The function rand_int(n,m)provides a random integer within the range n to m inclusive. rand_int(n,m)uses the seed described above.

The mathematical processing that is available is similar to that provided within the Moodle Gradebook and includes

• average(a, b…): Returns the average of a list of arguments.
• max(a, b...): Returns the maximum value in a list of arguments
• min(a,b...): Returns the minimum value in a list of arguments
• mod(dividend, divisor): Calculates the remainder of a division.
• pi(): Returns the value of the number Pi.
• round(number, count): Rounds a number to a predefined accuracy.
• sqrt, abs, ln, log, exp
• sin, sinh, arcsin, asin, arcsinh, asinh
• cos, cosh, arcos, acos, arccosh, acosh
• tan, tanh, arctan, atan, arctanh, atanh

Archivo:Figura 5 17.jpg Recalculate now will calculate a set of values

With all variables specified the ‘recalculate now’ button will calculate a set of values within the greyed out boxes.

Archivo:Figura 5 18.jpg Scientific notation can be demanded.

It is possible to require the student to enter their response using scientific notation. The input box is provided with a superscript facility and all of the following formats are accepted: 1.234e5, 1.234x105, 1.234X105 and 1.234*105.

For keyboard users the superscript may be accessed with the up-arrow key. Down-arrow returns entry to normal. You may wish to include this information within your question. If you do please note that the up-arrow and down-arrow provided in the HTML editor’s ‘insert custom characters’ list are not spoken by a screen reader and you should also include the words ‘up-arrow’ and ‘down-arrow’.

Archivo:Figura 5 19.jpg Figure 5.19 A numerical response matching example

Respuesta: This may be a numeric value, a variable as above or a mathematical expression. For the example shown here it would have been quite acceptable to place ‘a/(-b)’ in the Answer box.

Error aceptable: Computers store numbers to a finite accuracy e.g. 1/3 is stored as a finite number of recurring 3s in 0.33333… When used in calculations these minor infelicities can soon propagate and as such we strongly recommend that answers are matched within a suitable numerical range as shown here.

Decimales significativos: It is possible to request that responses be given to a specified number of significant figures.

Dealing with responses that are partially wrong

Typically these are responses that have a variation on the correct numerical value e.g.

• are not in scientific format when this has been reqiested
• have an incorrect number of significant figures
• are wrong by a factor of 10
• have been rounded incorrectly.

In all of these four cases specific feedback can be supplied using these settings.

Respuestas no-anticipadas

At the end of the response matching sequence you must deal with all the wrong answers that students will come up with. These may be ‘matched’ by using the ‘*’.

Archivo:Figura 5 20.jpg Figure 5.20 Dealing with all other numeric answers

Documentación detallada

Vea http://labspace.open.ac.uk/mod/oucontent/view.php?id=470268&section=5.2.3 para la página original en inglés de donde se tomó esta información

Vea también

• More documentation is available in the Open University's reference manual.
• Source control URL