PreTeXt Sample Book Abstract Algebra (SAMPLE ONLY)

                      <section xml:id="exercises-timed">

                        <title>Exercises that are Timed</title>

                        <p>
This is a section that merely explains and holds an <tag>exercises</tag> division, which will be at the level of a <tag>subsection</tag>.  There is a <attr>time-limit</attr> attribute on <tag>exercises</tag>, set to the value <c>10</c>, which implies (a) the collection of (two) exercises is a <q>timed exam</q> when hosted on Runestone, and (b) a student will have 10 minutes to complete the collection.
                        </p>

                        <p>
Showing results, showing feedback, displaying a timer, and allowing pausing are all enabled by default.  To disable any of these features, set the corresponding attributes on the <tag>exercises</tag> division, <attr>results</attr>, <attr>feedback</attr>, <attr>timer</attr>, <attr>pause</attr>, to the value <c>no</c>.  As a test, we have turned off pausing.  Don't panic!
                        </p>

                        <p>
Of course, if you are not viewing this while online and hosted on a Runestone server, then these exercises will not look any different than in other places.
                        </p>

                        <p>
(Since this is an unstructured division, the number of the <tag>exercises</tag> is not displayed when born.  It does <em>have</em> a number, which is the same as the enclosing <tag>section</tag>.  To wit: <xref ref="exercises-timed"/> versus <xref ref="timing-exercises"/>.)
                        </p>

                        <p>
If you prefer that a given <tag>section</tag> has more than one <tag>exercises</tag> within it (timed or not), realize that you must then structure your <tag>section</tag> with a ssequence of <tag>subsection</tag> as peers of the multiple <tag>exercises</tag> you desire.
                        </p>

                        <exercises xml:id="timing-exercises" label="timed-exercises" time-limit="10" pause="no">

                        <title>Timed Exercises</title>

                        <introduction>

                          <p>
You have 10 minutes to do these exercises when hosted online on a Runestone server.
                          </p>

                        </introduction>

                        <exercise label="vector-space-dimension-timed">

                          <title>True/False</title>

                          <idx>vector space</idx>

                          <statement correct="no">

                            <p>
Every vector space has finite dimension.
                            </p>

                          </statement>

                          <feedback>

                            <p>
The vector space of all polynomials with finite degree has a basis, <m>B = \{1,x,x^2,x^3,\dots\}</m>, which is infinte.
                            </p>

                          </feedback>

                          <hint>

                            <p>

                              <m>P_n</m>, the vector space of polynomials with degree at most <m>n</m>, has dimension <m>n+1</m> by <xref ref="theorem-exponent-laws"/>.  [Cross-reference is just a demo, content is not relevant.]  What happens if we relax the defintion and remove the parameter <m>n</m>?

                            </p>

                          </hint>

                        </exercise>

                        <exercise label="multiple-choice-not-randomized-timed">

                          <title>Multiple-Choice, Not Randomized, One Answer</title>

                          <idx>stop signs</idx>

                          <statement>

                            <p>
What color is a stop sign?
                            </p>

                          </statement>

                          <!-- to appear as problem with potentially multiple correct --> <!-- answers (even though there is only one), use           --> <!--                                                        --> <!--

                          <choices multiple-correct="yes">
                   --> <!--                                                        --> 
                            <choices>

                              <choice>

                                <statement>

                                  <p>
Green
                                  </p>

                                </statement>

                                <feedback>

                                  <p>
Green means <q>go!</q>.
                                  </p>

                                </feedback>

                              </choice>

                              <choice correct="yes">

                                <statement>

                                  <p>
Red
                                  </p>

                                </statement>

                                <feedback>

                                  <p>
Red is universally used for prohibited activities or serious warnings.
                                  </p>

                                </feedback>

                              </choice>

                              <choice>

                                <statement>

                                  <p>
White
                                  </p>

                                </statement>

                                <feedback>

                                  <p>
White might be hard to see.
                                  </p>

                                </feedback>

                              </choice>

                            </choices>

                            <hint>

                              <p>
What did you see last time you went driving?
                              </p>

                            </hint>

                            <hint>

                              <p>
Maybe go out for a drive?
                              </p>

                            </hint>

                          </exercise>

                          </exercises>

                        </section>