symbolic representation of a situation to another. In this case, the directed graph representation is to be transformed into a list of players ordered on the basis of their tournament records so far.

Presenting the task: If students are not already familiar with the directed graph notation, the teacher should introduce it (without the terminology "directed graph") as a means of displaying information about four students in a Tic-Tac-Toe tournament.

The teacher should explain the situation and ask simple questions such as:

Which students has Linda played? [Lourdes, Ed and Bob.]

Which games did she win? [The ones against Lourdes and Ed.]

Which games did she lose? [The one against Bob.]

Find two students who have not played against each other yet. [Lourdes and Ed; Ed and Bob.]

Who has played the fewest games? [Ed, with only one game played so far.]

Student assessment activity: The teacher should pass out copies of the student sheet and read through the introduction and question 1, to be sure that everyone has an understanding of the meaning of the dots and the arrows. A Spanish translation of the task appears immediately following the English version.



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