GraphPad: A Graph Creation Tool for CS2/CS7

摘要

This poster demonstrates an interactive software tool called GraphPad designed to facilitate interactivity in a CS2/CS7 course in which Tablet PCs or WACOM tablets are available. Using one of these devices users can use their own handwriting to construct graphs just as naturally as they would on paper without imposing restrictions. For example, drawing of nodes is accomplished by simply drawing a circle on the screen followed by the label to be associated with that node. Then a clean circle and formatted text will appear in the place of the user's handwriting. Drawing edges is accomplished in the same intuitive way. By drawing a line or arrow between nodes, an edge forms between the two nodes. These edges may also have weights/labels added to them. This freedom of structure enables teachers to get a good sense of how students might write answers on quizzes or tests. GraphPad allows teachers and students to interact in a number of unique ways. Instructors may conduct a synchronous exercises or different asynchronous exercises.rnDuring a synchronous exercise, GraphPad creates a local server on the instructor's computer. In addition, GraphPad starts an instance of an instructor client to communicate with the instructor server. Next, students use the instructor's IP address to connect to the instructor's server. This creates a unique student client which can communicate with the instructor's server. An instructor can now perform several tasks. He can send instructions/questions to the students' machines asking them to complete certain tasks. For example he can ask them to insert elements into a binary search tree or any other structure that can be represented as a graph. Once instructions have been given, both instructor and students work on creating the correct solution. A teacher can create a solution and add it to a list of correct solutions. After the students have completed their instructions, they submit their work to the teacher's computer. At any time the teacher has the ability to see the students' work and more importantly the ability to check their work. With a single click, GraphPad will check all of the students' work against all of the solutions created by the instructor. This will indicate to the instructor which students were correct or incorrect. In addition, students will get instant feedback telling them if their submission was correct or incorrect. This functionality is implemented using a simple form of graph isomorphism. Evaluations in a class of 25-30 students are typically returned to students within 5 seconds.rnDuring asynchronous exercises, teachers and students are able to interact in a different way. In these exercises, an instructor uses an authoring tool to create a series of questions/instructions. If a teacher wants to include a certain question in the exercise theyrnsimply ink or type the question into a specified box and continue. Once the instructor has completed entering all of the questions, the instructor will upload the entire exercise to a database. Now students will be able to view these exercises and try to complete them. Once the student has completed an exercise they submit their answers to a database for the teacher's evaluation later. The instructor has control over a number of variables when creating these exercises such as allowing students to go back during their exercise, preventing them from going forward until they have got the question correct, and allowing students to see the correct solution once the exercise is over.rnUnderneath this interactive functionality between teachers and students is a database that records all of the work being performed. This includes the graph structures drawn, the .annotations of the final submission, and the entire construction process. With this data GraphPad can replay student solutions for the teacher. The teacher can directly observe the cognitive process that a student undertakes to develop solutions. In this way, GraphPad provides functiona