Well you know that 1/2 will be in the middle of 0 and 1 so you can place that point, then 2/3 is just a little bigger than that so you can divide your whole number line (of 0 to 1 ) into three sections and place 2/3 on the second line, then, 3/8 is almost 4/8=1/2 so just put it a little below your 1/2 point