About: http://webisa.webdatacommons.org/424463302

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Lenses are made of transparent materials, such as glass or plastic, with an index of refraction greater than that of air.
http://www.w3.org/ns/prov#wasQuotedFrom	ck12.org