transparent sheet printed with a grid of dots
... that one can accurately estimate the area of irregular objects such as plant leaves using only a transparent sheet printed with a grid of dots?
... that one can accurately estimate the area of irregular objects such as plant leaves using only a <b id="mwBcM"><a href="./Dot_planimeter" id="mwBcQ" rel="mw:WikiLink" title="Dot planimeter">transparent sheet printed with a grid of dots</a></b>?