"the femur is the biggest bone in the body so the thigh is the longest part of the leg"
INCORRECT!!! don't get tripped up by that
while your femur IS the longest bone, it overlaps into your hip. so is the calf longer or the thigh? it actually varies person to person! my calves are longer than my thighs. so when drawing a character with correct proportions, make sure to decide that stuff and put it down somewhere for consistency!