Keep Calm and Show Your Work Funny Math Teacher Gift T-Shirt Solid colors: 100% Cotton; Heather Grey: 90% Cotton, 10% Polyester; All Other Heathers: 50% Cotton, 50% Polyester Imported Machine wash cold with like colors, dry low heat Keep Calm and Show your Work! Funny Teacher Appreciation gift for a math or algebra teacher who insists on detailed explanations of problems. Lightweight, Classic fit, Double-needle sleeve and bottom hem