(Portland, OR)  --  Parents of students at a Portland charter school are holding a rally today to protest the police use of tear gas against demonstrators at the nearby ICE building.  Parents at The Cottonwood School of Civics and Science say the school's playground will be closed today because of the police deployment of tear gas on Saturday night.  Today is the students' first day back in the classroom.  Parents say they're concerned about the effects of tear gas residue on their children.