Arnold Danielson, a chemistry teacher at Warren G. Harding High School, has for the past eight years used custodian Howard Sievert as a living warning to underachieving or misbehaving students. 'When my grades started to slip, Mr. Danielson took me aside and said, 'Well, you can buckle down and study harder... or you can end up like old Howie,'' sophomore Dave Netzel said. 'Boy, I got the hint big-time.' Netzel said Danielson is also fond of asking tardy students to name their favorite car and then informing them that such a car is unaffordable on a janitor's salary. 