I'm going to start with an example: On her way to school, a child discovered that her loonie is missing and there is a hole in her pocket. She turned back and walked 24 m east along the sidewalk. Then, she stopped for 18 s and decided to head back to school. After walking 11 m west, she found the loonie. If the child walked at a speed of 0.25 m/s, calculate, a) her average velocity while searching for the coin? b) her average speed while searching for the coin? Obviously there are two parts where the student travelled. First part: x1=24m v1=0.25m/s t1=96s (after calculation) Second part: x2=11m v2=0.25m/s t2=44s (after calculation) If I wanted to find the average velocity then I would use my velocity formula: (avg)v = (x2 - x1) / t2 - t1 but I have to be careful because writing (avg)v = (11m - 24m) / (96s - 44s) is wrong!!! Is this a common mistake? Should I name my variables differently?