Back to School or End of Year Thinking Math Task. STOP THE ALIENS. This perfect squares and square roots activity is a math challenge that is designed to help students practice their perfect squares and square roots. In this activity, students will use their knowledge of perfect squares of numbers 3-15 and square roots of perfect squares 9-225 to STOP THE ALIENS. Aliens have attacked the Earth and they want to destroy the human race.You must stop this invasion before the Earth is destroyed. Yo