Pi_book provides scaffolding contents about exhibitions in a museum with PDAs. Scaffolding contents in PDAs are interactive in order to attract children's attention to exhibitions and PDAs. Children can learn difficult scientific phenomina through interacting exhibitions and PDAs.

Musex is proved to be an effective system to support children's learning activities in a museum. However, we also discovered some points to be improved in Musex. For example, contents which Musex provides to children are limited to exhibition-related quizzes. They are reasonable materials for children to think about exhibitions in front of them deeply, but they are not very attractive or interactive. Some children want more interactive contents in PDAs. Anthoer problem is that some children have difficulty in finding out RFID tags which are installed near exhibitions. One of the reason is that tags are hidden by other visitors(adults) and children can't see the tags. Therefore, a method to solve this problem is required. To compensate for these points, we devised Pi_book, a system that provides children attractive and interactive contents in a museum.

Fig. 1 Pi_book system

Fig. 1 shows the architecture of Pi_book. Pi_book is comprised of PDAs and Cobit(Compact Battery-less Information Terminal). Cobit consists of light emitters and receivers, and provides acoustic information to users who wear receivers. Acoustic information is changed into electrical signals and emitted from light emitters as infrared light. A receiver has a solar cell that can receive infrared light and utilizes the optical energy to generate acoustic information for the user. Therefore, when a receiver receives infrared light, a user can hear sound from a receiver. For more detail, please see Takuichi Nishimura's website .

Cobit light emitters and RFID tags are installed near exhibitions. Therefore, children can find RFID tags by listening sound from Cobit light emitters even if they cannot see RFID tags. They let their PDAs close to the tag in front of them, and an interactive content will be shown in their PDAs like Fig. 2. Some of these contents are like games, some are like guessing quizzes, and some are like interactive explanatory animations. These are related to exhibitions, so children can enjoy learning difficult phenomina from PDAs and exhibitions that are less interactive.

Fig. 2 screenshots of Pi_book

Fig. 3 Pi_book in use

We evaluated Pi_book in National Science Museum in March 2003. In this experiment, we set up 9 exhibition-related contents. Before and After using Pi_book, children answered a questionnaire about Pi_book. And we videotaped children's activities for the discussion. Fig. 3 shows children's activities in the museum with Pi_book.

Analying from questionaires and videotapes, we discovered some interesting aspects of Pi_book.

• Through communicating with friends or parents about exhibitions and contents on PDAs, children can make their understanding deeper.
• Without talking about exhibitions so much, even if communication is enough, children couldn't success fully deepen their understanding about the exhibitions.
• Children pay their attention to exhibitions from various points of view. For example, some children watch exhibitions in front of them because they want to complete games successfully. Some because they have an interest in certain scientific phenomina through PDAs and want to know more about them.