Period 6 element devices though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alcohol-filled, galinstan-filled, digital, or thermistor-based instruments. It remains in use in scientific research applications and in amalgam material for dental restoration. It is used in lighting: electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light. Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray other metal resembles tin but discolors when exposed to air. The
Problem-posing education Problem-posing education Problem-posing education is a term coined by Brazilian educator Paulo Freire in his 1970 book "Pedagogy of the Oppressed". Problem-posing refers to a method of teaching that emphasizes critical thinking for the purpose of liberation. Freire used problem-posing as an alternative to the banking model of education. Freire's pedagogy emerged from his observations and experiences working as an instructor in literacy programs with peasant laborers in Brazil. During this work, Freire became aware of the economic, political, and social domination resulting from paternalism. Paternalism leads to a culture of silence, which keeps people from confronting their oppression. He