414 Y. Wang and K. Li In the situations above, we proposed a theme-based online collaborative learning model, which integrated the online thematic and collaborative learning. Then, guided by the model, we developed an online learning system, and performed a case study which can intuitively analyze the varying tendency of the participation in five stages of group lifecycle in some online collaborative learning activities, such as collecting and sharing learning resources, communications in online virtual forums, and so on. Finally, we drew some conclusions and discussed some future works about the system. 2 System Design 2.1 An Online Theme-Based Collaborative Learning Model: OTBCL Model Based on the definitions and instruction design of online thematic and collaborative learning, we proposed an online thematic collaborative learning model, named OTBCL model acronym of Online Theme-Based Collaborative Learning (Fig. 1). The model is composed of three circles: outside circle, middle circle and inner circle. In the outside circle, there are eight explicit learning activities, which are typical and necessary steps to carry out an online thematic collaborative learning. In the middle circle, it is learning portfolios that serve as tools scaffolding introspection of learners and evaluation of teachers. The learning portfolios are represented by some participa- tory indicators which are educed by learners’ actions tracked and logged in outer circle. Inner circle includes the processes of reasoning and thinking in the mind of learners: plan, action and reflection. In the overview of the model, the learning portfo- lios in the middle circle, which serve as social media and technology tools, support and facilitate the process between interpersonal socialization in the outer circle and mental internalization in the inner circle. Choose a theme Collect, transform and share learning resources Communicate and collaborate Synthetize group work Sharing learning fruits Evaluate collaborative learning activities Assign group task Identify individual roles Design group learning activities Form learning groups Action Plan Refelction Learning portfolio Learning portfolio Fig. 1. An online theme-based collaborative learning model (OTBCL model) An Online Theme-Based Collaborative Learning System 415 The typical steps of online theme-based collaborative learning are explained below: Choosing a theme. The choice of a theme is central to the ultimate success of the project [1]. In this phase, teachers analyze the goals and contents of a curriculum, and divide the curriculum into several learning themes which have definite goals and specific tasks. There are three principles when choosing a theme: 1) the theme is based to one problem or project; 2) the goals of the theme is attainable and measur- able; 2) the tasks of theme are practicable and can be divided into several subtasks. Forming learning groups. Groups can be formed in many different ways: lecturer assigned groups, students self-select, and random allocation/selection [6]. The size of a group usually is not more than 8 members. Besides, when forming a group, it is necessary to assign a member to be the leader of the group, who manages the learning affairs and coordinates the correlations between members in the group. Assigning group tasks and identifying individual roles. Based on the goals and tasks of the theme, the members of a group need to further set up its goals and impose its tasks by communicating each other. Then, members divide tasks of the group into several subtasks, and assign a certain role to each member who is charge with one or more subtasks. Designing group learning activities. Learning activities are the schemes and scaf- folds of collaborative learning process. Designing group learning activities means transforming the tasks into a number of learning events which are arranged by a rea- sonable schedule. Therefore, in this phase, members need give their attention to these aspects: the sequences of learning events, rationality of the timetable, the definite outcomes in each learning event. Besides, the states of learning activities should dy- namically show the actual progress of learning event in real time. When a certain learning event is dropped behind the schedule of learning activities, members of the group will be reminded in time. Collecting, transforming and sharing learning resources. Learning resources pro- vide contents for members of learning groups. At the beginning of this phase, lec- tures/tutors need provide some learning resources about the theme, which can make students understand the basic knowledge about the theme. Then, members of each group collect their learning resources by web searching engines, such as Google, Yahoo, Msn and so on. Students construct their individual knowledge by assimilating learning resources, and share the learning resource in the group private or class public resource repositories. Finally, members can rate and comment the learning resources shared by their peers. Communicating, collaborating and synthesizing group work. Interactions and communications rare the most important and fundamental components in online col- laborative learning. Forming of individual identity, appearing of shared values and accumulating of learning outcomes are built on them. In addition, by discussing the concepts, doubts and questions in learning themes, members of the group synthesize their individual work into group work collaboratively [7]. 416 Y. Wang and K. Li Sharing learning fruits among groups. After finishing group’s work, members of the group need to share their learning fruits with the other groups in the class. On the other hand, members of other groups can rate and comment the learning fruits of the group. The score of the group work is an index to evaluate task-based performance of the group. Evaluating collaborative learning activities. There are two kinds of methods to evaluate the task-based collaborative performance, one is teacher evaluation, and the other is peers evaluation. In the moel, we integrated the two kinds of evaluation method. Firstly, members of a group score and remark the other members of the same group. Then the teacher of the class evaluates each member based on the scores and remarks from their peers and indicators in the learning portfolios. 2.2 System Architecture Guided by the OTBCL model described in above section, we designed the architec- ture of the system (Fig. 2), which is composed of eight modules: theme basic informa- tion module, task assignment module, learning resources module, learning activities module, interaction module, learning fruits module, learning portfolio module and evaluation module. The main modules are described briefly below: Fig. 2. Architecture of the system Theme basic information module. Once a teacher chooses a theme, he/she will define the basic information of the theme, such as the title and descriptions, goals and tasks, the starting and ending time, and so on. Task assignment module. The functions of the module include: forming the groups, assigning group task, identifying the individual roles and responsibilities. The module support three ways of forming a group: lecturer assigned groups, students self-select, and random allocation/selection by system. Theme Basic Information Module Task Assignment Module Learning Portfolio Module Evaluation Module Short Messa g e Online Forum Wiki Chat Room Interaction Module Learning Portfolio Module Learning Resource Module Learning Fruits Module An Online Theme-Based Collaborative Learning System 417 Learning resources module. In this module, there are two kinds of learning resource repositories: 1) one is group private where members in the same group share and comment resources; 2) the other is class public where the resources shared by mem- bers of a group can be read, downloaded, modified, and commented by the all the students of the class. Besides, the module provides powerful searching functions for the members to search their needed resources. Learning activities module. The leader of a group can design the learning activities which is composed of a number of learning events. All the learning events are schemed by a timetable. Besides, the sequences, the starting and ending time of learn- ing event of learning activities can be changed by the leader of a group. Interaction module. There are four kinds of tools supporting the interactions and communications among members of a group. The BBS and Wiki support asynchro- nous communication, the chat-room supports students’ synchronous communication, and the short message tool supports both kinds of communications. All the actions, such as posting, reading, replying, and building on, are tracked and logged into the database of the system. The details about the process will be explained in the next section. Learning fruits module. Groups can present and share their group learning fruits with other groups of the same class in the class public workspace. On the other hand, members of a group can share their personal learning fruits with their peers in the group private fruits workspace. Moreover, members of groups can rate learning fruits of other groups with five grades: best, better, medium, worse, and worst. Learning portfolio module. This module consists of two sub learning portfolios, one is group learning portfolio which archives the interacting behaviors and collaborative works of a group, the other is member’s individual leaning portfolio which archives those of every member of the group. The specific indicators in learning portfolio will be discussed in the fourth section of this part. Evaluation module. In this module, we can assess the task-based performance of online collaborative learning. As described in the OTBCL model, the integrated evaluation can conduct peers evaluation and teacher evaluation. 2.3 User Interface Design The interface of collaborative learning system must meet with four principles: 1) is convenient to operate for users, 2) can easily track and log users’ actions, 3) can navi- gate a user to further take actions, 4) can effectively support and scaffold collabora- tive learning task. Two examples of interface design are represented below: In the first example, the notes posted by members in online virtual forums are dis- played with a tree structure. The design has many benefits. Firstly, a student, at a glance, will perceive and understand the outline and structure of knowledge repre- sented. Secondly, the system will log the reading action into database when a student clicks the note’s hyperlink to read the content of it. Thirdly, the interface display different levels of knowledge with different image icons and colours, which scaffolds the met cognition of students. 418 Y. Wang and K. Li Fig. 3. Tree structure of notes Fig. 4. User interface for posting notes In the second example, we designed the interface where members post a note in the online virtual forums, as illustrated in figure 4. When a member posts his/her notes, he will classify it one of five knowledge construction levels in the interaction analysis model [6]. And after he selects one level in the classification, the system will auto- matically generate the corresponding thinking scaffolds. In this study, thinking scaf- folds are composed of all kinds of sentence openers representing different implica- tions and situations, which can guild students to construct high level knowledge. In addition, eWebEditor, a kind of multimedia editor based web, is embedded into the interface, so students can publish notes with images, animations, sounds, videos and so on. 2.4 Learning Portfolio Design Referring to the unified framework of interaction analysis [8], we designed the schemes of learning portfolio formation, as shown in the figure 5. Learning activities influence the choice of indicators used to conduct further analysis. Indicators chosen in learning activities determines the design of system interfaces, which is responsible . circle. Inner circle includes the processes of reasoning and thinking in the mind of learners: plan, action and reflection. In the overview of the model, the learning portfo- lios in the middle. event in real time. When a certain learning event is dropped behind the schedule of learning activities, members of the group will be reminded in time. Collecting, transforming and sharing learning. structure of notes Fig. 4. User interface for posting notes In the second example, we designed the interface where members post a note in the online virtual forums, as illustrated in figure