The proposed wall along the U.S.-Mexico border would significantly affect wildlife. Most animals cannot get past walls that are hundreds of miles long and many meters tall. Some species along parts of the border where a wall already exists, such as jaguars and ocelots, suffer from dwindling populations and difficulty finding mates. This column focuses on making teaching more environmentally friendly. This month's issue discusses how the proposed wall along the U.S.--Mexico border would significantly affect wildlife.