The authors made a demonstration model to explain the amplification of sound by the area ratio of tympanic membrane vs round window, and studied the effect of the use of this model for the understanding of students in the class at a medical vocational school. The model was made using a mechanical cooking scale with a styrene disk and a commercially available toy air-gun. For the purpose of generating the force, the proper size of the styrene disk, the proper distance between styrene disk and the air-gun and the proper caliber of the air-gun were examined. Furthermore, the comparison was made between the toy air-gun and a self-made air-gun in generating the force. From the result of the examination, 20 cm and 5cm for the diameter of tympanic membrane and for that of round window, 40 cm for the distance from the air-gun to the disk, and 12 cm for the caliber of air-gun were selected. Demonstration using the commercially available toy air-gun was conducted with the above described condition. After the lecture, the question " where is the sound amplified in the human auditory system?" was asked to the students. The ratio of the students who answered correctly, " it is in the ossicle" increased significantly compared to the ratio of the correct answers given before the lecture. However, there was no difference in the result with or without the use of this model. To the question "how does the auditory system amplify the sound?" the ratio of the students who answered correctly, " it is amplified by the work of the lever" increased compared to the ratio of the correct answers before the lecture. Although when the model was not used in the lecture, no students answered " the area ratio of the tympanic membrane vs the round window", with the use of the model, the ratio of students who answered correctly increased significantly. The authors assumed that the use of this model has contributed to students' better understanding of the amplification of the sound by "lever action" as well as the understanding of "the area ratio of the tympanic membrane vs the round window".

DNA replication is one of the important subjects of high school biology course. In the new national curriculum framework, the Course of Study (CS) for secondary schools, emphasis will be placed on molecular biology subjects. The purpose of this study is to develop new biology education material for molecular biology including DNA replication mechanism being applicable to high school biology course. DNA fiber is one of the important methods in molecular biology to elucidate DNA replication initiation and progression mechanism. We have here improved DNA fiber method to be applicable for using teaching material on high school students. Improved DNA fiber method was implemented in the course of science program of one Japanese high school. After the completion of implementation, students were able to have some interest to the DNA replication, especially through visualization of molecular phenomenon. We propose here this kind of visualizing teaching materials for molecular biology should be effective for teaching in high school biology course.

For an elementary school children, observation of animal behavior would be important to understand life history of animals. In the present study, we developed teaching materials for the understanding of respiration, especially differences between branchial and pulmonary respirations. Tadpoles of the American bull frog (Rana catesbeiana) generally take dissolved oxygen from water by branchial respiration and through skin. However, if dissolved oxygen in water is low, they sometimes perform air breathing with pulmonary respiration. To understand the change from branchial respiration to pulmonary respiration in tadpoles, we manipulated conditions (abiotic conditions [water pressure, oxygen concentration, and carbon dioxide concentration], biotic conditions [quantity of motion, population density, and developmental stage]) of tank where tadpoles were introduced, and counted the number of air breathing. We also compared the number of air breathing among different developmental stages of tadpoles, because it is supposed that tadpoles during metamorphosis would increase the dependency on pulmonary respiration. The number of air breathing behavior of tadpoles clearly increased when the dissolved carbon dioxide was increased. This indicates that when dissolved oxygen in water is low, brachial respiration is not useful and tadpoles use pulmonary respiration to take the oxygen from air. As the developmental stage prodeeded, the number of air breathing behavior increased. This would reflect physiological transitions during the metamorphosis in which lungs are developing and gills are disappearing. Air breathing behavior of tadpoles is easily observed. By making this experiment with tadpoles, elementary school children would understand the respiration of animals. We emphasized that observation and experiment of animal behavior would be important as teaching materials at elementary school.

Each of the mature pollen grains of Hymenocallis littoralis has been shown to contain a reddish brown, spindle-shaped generative cell. The present study revealed that the behavior of generative cells and sperm cells within pollen tubes could be observed under the conventional light microscope. About three hours after pollen dispersal on the surface of agar plate, the generative cell entered the pollen tube, maintaining its shape and color. The generative cell divided into two reddish brown sperm cells at 7-9 hours after pollen dispersal. These sperm cells moved toward the tip of elongating pollen tube. Based on the present observation, possible application of the pollen of H. littoralis as a material to the classes for teaching the double fertilization characteristic of the angiosperms in high school biology is discussed.