Faraway places are not unfamiliar to the students at Boston International High School. But melting glaciers in the Arctic and climate change? That was a foreign concept for Caitlin MacLeod-Bluver to convey to her 10th-grade students — at least until now. MacLeod-Bluver was one of 35 educators chosen out of more than 300 applicants to receive a National Geographic Grosvenor Teacher Fellowship. In June, MacLeod-Bluver will travel aboard the National Geographic Explorer to Arctic Svalbard on an expedition to the “Land of the Ice Bears” — part of an 11-day journey to study the effects of climate change.