5:15 PM - 7:15 PM
[G04-P06] Development of teaching materials focusing on the "floating property on water" and “amorphous nature” of pumice
Keywords:Fukutoku-Oka-no-Ba, pumice, development of teaching material, floating property on water, amorphous
1 Introduction
In August 2021, a large eruption occurred at Fukutoku-Oka-no-Ba. The large amount of pumice generated by the eruption formed pumice rafts that drifted to the coasts of Okinawa and other parts of Japan (e.g. Chang et al. 2022; Yoshida et al. 2022). Japan is a famous country for having numerous volcanoes, thus it is desirable to learn the effects of volcanoes on human life in school education. This study aims to develop new teaching materials using the material properties of pumice. In particular, this presentation will focus on the "floating property on water" and "amorphous nature" of pumice.
2 Development of the teaching material focusing on the "floating property on water" of pumice
2-1 About the teaching material
For porous samples such as pumice, it is important to distinguish between apparent density and true density. Pumice floats in water because its apparent density is smaller than that of water. When water displaces the pumice pores, the apparent density increases. Then, pumice could sink when the apparent density becomes higher than that of water.
2-2 Experimental Methods
Water was poured into the jar to 6th-8th fill and a pumice stone was floated on the water. After attaching the lid and depressurizing the jar, numerous bubbles were observed from its open pores at first. When no bubbles could be observed, the decompression was stopped, and the inside was returned to atmospheric pressure. When residual atmosphere that had expanded under depressurized inside shrink, water can penetrate in the open pores. As a result, the apparent density of the pumice stone increases, and when it exceeds the density of water, it sinks.
2-3 Classroom Practice
The teaching material was used in a 90-minute class for teacher-training course university students majoring in a non-science subject. At first, I explained that volcanic phenomena are inseparable from our daily lives for Japanese people. Next, a water tank experiment simulating a large-scale volcanic eruption by Kasama et al. (2011) was demonstrated, and volcanic ejecta were introduced. After that, the students performed the experiment using this material.
At the beginning of the experiment, I described the eruption at Fukunoku-Oka-no-Ba and introduced the response of Okinawa Prefecture. The central question was, "Why do pumice stones float in water (even though they are 'stones')?" Next, the students performed the experiment and observed the behavior of pumice. After the experiment, they answered the same central question again. The results and discussion will be presented on the day of JpGU 2025.
3 Development of teaching materials focusing on the "amorphous nature" of pumice
3-1 About the teaching material
Pumice is one of the volcanic ejecta, which can be formed by rapid cooling during explosive eruptions. Therefore, most part of the pumice is amorphous. The amorphous nature of pumice has been utilized for glaze of ceramics (e.g. Terao and Sawasaki, 1996). Kanzaki (2007) practiced cloisonne ware making at a high school using an electric furnace. We decided to investigate a method of making glazes using pumice from Fukutoku-Oka-no-Ba with school facilities, and to plan a class using this method.
3-2 Experimental Methods
The basic glaze was made by mixing crushed Fukutoku-Oka-no-Ba pumice, Gairome clay, and calcium carbonate to produce a transparent, crystalline, or matte glaze based on the Zegel equation. Lead-free frit was added as a melting point depressant. Glaze spread with water was applied thinly to unglazed chips and placed in the crucible. The crucible was placed in a gas burner muffle and heated to red heat. After the required heating time, the gas burner was turned off and the cooled samples were collected.
3-3 For educational practice
In educational practice, we can teach that the most part of pumice is amorphous material formed by a rapid cooling process. Additionally, students can consider the relationship between volcanoes and human life.
In August 2021, a large eruption occurred at Fukutoku-Oka-no-Ba. The large amount of pumice generated by the eruption formed pumice rafts that drifted to the coasts of Okinawa and other parts of Japan (e.g. Chang et al. 2022; Yoshida et al. 2022). Japan is a famous country for having numerous volcanoes, thus it is desirable to learn the effects of volcanoes on human life in school education. This study aims to develop new teaching materials using the material properties of pumice. In particular, this presentation will focus on the "floating property on water" and "amorphous nature" of pumice.
2 Development of the teaching material focusing on the "floating property on water" of pumice
2-1 About the teaching material
For porous samples such as pumice, it is important to distinguish between apparent density and true density. Pumice floats in water because its apparent density is smaller than that of water. When water displaces the pumice pores, the apparent density increases. Then, pumice could sink when the apparent density becomes higher than that of water.
2-2 Experimental Methods
Water was poured into the jar to 6th-8th fill and a pumice stone was floated on the water. After attaching the lid and depressurizing the jar, numerous bubbles were observed from its open pores at first. When no bubbles could be observed, the decompression was stopped, and the inside was returned to atmospheric pressure. When residual atmosphere that had expanded under depressurized inside shrink, water can penetrate in the open pores. As a result, the apparent density of the pumice stone increases, and when it exceeds the density of water, it sinks.
2-3 Classroom Practice
The teaching material was used in a 90-minute class for teacher-training course university students majoring in a non-science subject. At first, I explained that volcanic phenomena are inseparable from our daily lives for Japanese people. Next, a water tank experiment simulating a large-scale volcanic eruption by Kasama et al. (2011) was demonstrated, and volcanic ejecta were introduced. After that, the students performed the experiment using this material.
At the beginning of the experiment, I described the eruption at Fukunoku-Oka-no-Ba and introduced the response of Okinawa Prefecture. The central question was, "Why do pumice stones float in water (even though they are 'stones')?" Next, the students performed the experiment and observed the behavior of pumice. After the experiment, they answered the same central question again. The results and discussion will be presented on the day of JpGU 2025.
3 Development of teaching materials focusing on the "amorphous nature" of pumice
3-1 About the teaching material
Pumice is one of the volcanic ejecta, which can be formed by rapid cooling during explosive eruptions. Therefore, most part of the pumice is amorphous. The amorphous nature of pumice has been utilized for glaze of ceramics (e.g. Terao and Sawasaki, 1996). Kanzaki (2007) practiced cloisonne ware making at a high school using an electric furnace. We decided to investigate a method of making glazes using pumice from Fukutoku-Oka-no-Ba with school facilities, and to plan a class using this method.
3-2 Experimental Methods
The basic glaze was made by mixing crushed Fukutoku-Oka-no-Ba pumice, Gairome clay, and calcium carbonate to produce a transparent, crystalline, or matte glaze based on the Zegel equation. Lead-free frit was added as a melting point depressant. Glaze spread with water was applied thinly to unglazed chips and placed in the crucible. The crucible was placed in a gas burner muffle and heated to red heat. After the required heating time, the gas burner was turned off and the cooled samples were collected.
3-3 For educational practice
In educational practice, we can teach that the most part of pumice is amorphous material formed by a rapid cooling process. Additionally, students can consider the relationship between volcanoes and human life.