**5.2 Set up of a CRS using optical touch screen devices**

With the above needs in mind, we applied the optical touch screen to the development of the next generation CRS, or Z-Writers. The major part of the Z-Writer is a clipboard style writing surface. Students can put a regular notepad or a stack of test paper on it. They can write on the paper just like what they are doing in the regular test. The difference of the Z-Writer from the regular clipboard is that a sensor bar is installed at the top of the pad. The sensor bar can take either the PLUS or PLUM configuration as shwon in Figure 7A or Figure 7B.

Fig. 7. Hardware setup.

Like tablet PCs or xPads, the Z-Writer can be used by individual users. That is, each Z-Writer is associated with a computer via Bluetooth wireless connection. Since only the movement of the pen tips will be recorded and transmitted, no high capacity data transmission is required. Off-the-shelf mainstream Bluetooth 2.1 transmitters are capable of sending and receiving data without delay.

We can also network Z-Writers in a CRS setting. Each Bluetooth master can only handle up to 7 devices with today's technology. In Linux set up, we can simply add extra Bluetooth dongles to increase the number of devices the computer can handle. For Windows or Mac OS, the operating systems can not handle more than one Bluetooth master. Therefore, we developed a special Scatternet (Mockel et al, 2007) to expand the capacity of the Z-Writers.

As seen in Figure 8, we divide all the Z-Writers in a classroom to groups of 6. One of them equips a sub-server with an enhanced antenna. It acts as both a receiver and a relay. It collects the data from the group and relay them to the Bluetooth master in the host computer. In this network, each computer can handle up to 7 groups or 42 Z-Writers. That is enough for most classes and more than the maximum capacity that a teacher can handle at the individual level without a teaching assistant. For the larger classes with the help of teaching assistants, a local network of multiple computers or an outright change to using 802.11 can be employed. However, these are beyond the topic of this discussion.

Fig. 8. Set up of a Classroom Response System.

128 Virtual Reality and Environments

operating system in one classroom unless they are provided for free. Third is the distraction of the other software, especially the communication and entertainment software installed in the tablets. When a student is having an electronic device in hand, it is not easy to resist the temptation of returning a quick text message or playing a small game while the teacher is

With the above needs in mind, we applied the optical touch screen to the development of the next generation CRS, or Z-Writers. The major part of the Z-Writer is a clipboard style writing surface. Students can put a regular notepad or a stack of test paper on it. They can write on the paper just like what they are doing in the regular test. The difference of the Z-Writer from the regular clipboard is that a sensor bar is installed at the top of the pad. The sensor bar can take either the PLUS or PLUM configuration as shwon in Figure 7A or

Like tablet PCs or xPads, the Z-Writer can be used by individual users. That is, each Z-Writer is associated with a computer via Bluetooth wireless connection. Since only the movement of the pen tips will be recorded and transmitted, no high capacity data transmission is required. Off-the-shelf mainstream Bluetooth 2.1 transmitters are capable of

We can also network Z-Writers in a CRS setting. Each Bluetooth master can only handle up to 7 devices with today's technology. In Linux set up, we can simply add extra Bluetooth dongles to increase the number of devices the computer can handle. For Windows or Mac OS, the operating systems can not handle more than one Bluetooth master. Therefore, we developed a special Scatternet (Mockel et al, 2007) to expand the capacity of the Z-Writers.

**5.2 Set up of a CRS using optical touch screen devices** 

not around.

Figure 7B.

Fig. 7. Hardware setup.

sending and receiving data without delay.

The host computer on the teacher's side collects all the data from the sub-servers and save them into a database. A preview program converts the data into pixel points and display them in a preview window like the left part of Figure 9. With a quick glance, the teachers can have an instant view of how the students are performing. When the teachers need to annotate an individual student's work, they can select and magnify the one of interest and display it as seen in the right half of Figure 9 for in-class review and analysis.

Fig. 9. Display in teacher's computer screen. Left: Real-time preview with all inputs. Right: Magnified view of individual answers.

Optical Touch Screen and Its Application as a Next Generation Classroom Response System 131

4. **3D input**. As mentioned earlier in this article, the action space and virtual force can be

5. **Multi-touch**. Existing computer software can easily detect and follow multiple image features. It will be easy to include multi-touch functions. Combined with virtual force,

6. **Compact and light weight**. Comparing to the existing optical touch screen using behind screen or user side camera, this side camera method is compact and can save precious space. The cameras are generally small and will not increase the weight or size

1. **Real-time feedback.** All educators are facing the perpetual challenge of assessing how well the students understand each course, each example, or even each sentence. Homework, quizzes and exams evaluate each individuals but with latency. Group discussion, flash cards, and the original Classroom Response Systems (Clickers) provide instant but collective feedbacks. The Z-Writer Group combines the benefits of the two

2. **Progress monitor.** From one computer display, teachers can monitor not only the answers but how the students proceed from start to finish at both collective and

3. **After-class evaluation.** Teachers can replay the writings of every answer after the class. Therefore, they can analyze each student and address their specific needs with higher

4. **Open-ended questions.** Many in-class assessment tools rely on multi-choice questions, which are not enough for STEAM subjects. The Z-Writer Group will enable teachers to give open-ended questions in classes and obtain real-time feedbacks. This will greatly

Currently we are working on improving the stability and noise reduction on the optical touch screen algorithm and its use on classroom response system described in this paper. We are also working on expanding the applications of the optical touch screen to art and calligraphy field for paperless painting with realistic strokes. We are also exploring the use

Albinsson, P & Zhai, S. (2003). High Precision Touch Screen Interaction, *Proceedings of the* 

*SIGCHI conference on Human factors in computing systems*, ISBN:1-58113-630-7, Fort

used to achieve the effect of 3D input and to obtain virtual force feedback.

the multi-touch function can make inputting more versatile and powerful.

of the computer display like many existing touch screens.

by providing instant individual feedbacks to the teachers.

encourage creativities from the students.

of 802.11 for the auditorium size CRS settings.

Lauderdale, FL, April 5-10, 2003

**6.2 Benefit of the next generation CRS using touch screen writers** 

height-width ratios.

individual levels.

accuracy.

**6.3 Future work** 

**7. References** 

viewable area quadruples, so is the material used and the computing power needed. In contrast, in the methods introduced in this article, the same two cameras or camera and mirror combination can be easily scaled up or down to screens with different sizes and

Figure 10 is a sample course material common to Physics or Engineering majors. One main topic of such majors is load analysis with Free Body Diagrams (FBD). Figure 10 gives a typical example of the force analysis. On left is a block resting on a slanted surface. As shown on right, students need to set up a proper coordinate system, draw the forces, and then write down the governing equations on each direction to find out the magnitudes of the forces.

Before the class, the teacher prepares questions like the one shown in the left part of Figure 10 and makes copies on regular paper. In the class time, the teacher first explains the concepts of FBD and provides examples. Then the handouts with the questions will distributed to the class. The students put the handouts on the writing surfaces of the Z-Writers and then write their answers on the paper just like any other classes. The Z-Writers transfer the results to the host computer for the teacher to review in real time. The teacher is then able to adjust the next step accordingly, such as revisiting the subject, moving on to the next topic, or giving annotations to selected answers. At the end of the class, the students will carry their own paper home while the teacher keeps a soft copy of all answers for future reference.

Fig. 10. A typical example of load and motion analysis. Left: Given by teacher. Right: Student answer.
