Right side is
井 'well' - the pictograph of a wooden well-frame. It supplies the sound - jǐng drifting to jiǎng with tone shift. The simplified
讲 is a heavy reduction of the traditional
講 (which had
冓 on the right, a 14-stroke graph of woven beams). The reform borrowed
井 purely for its sound; no semantic claim survives in the modern form.