Pre-course exercise: focus at different apertures

In this exercise you were asked to focus on the mid-point in a scene and take three pictures, one with the widest available aperture, one with the narrowest, and one in the middle.  The somewhat abstract results (the images depict a striped woven throw) are attached below.

All three images were taken at 44mm with the camera on aperture priority setting, meaning that the shutter speed was automatically decreased to maintain a constant exposure.

Image 1 was taken at f4.8 at 1/30.

Image 2 was taken at f10 at 1/8.

Image 3 was taken at f29 at 1.1s.

The first image has the smallest area of sharpness - the first eight bands of colour are blurred, and so are several at the back.  The second image is slightly sharper, with only the first four or five colour bands at each side out of focus; and the third image is the sharpest of all, with more or less all of the fibres clearly visible. 

Although I was quite fond of the images (particularly as a linked, undulating triptych!) I'm not sure this was the best subject to illustrate this technique.  Blurring at the top and bottom of the photos is not as obvious as on the left and right.  Something on a larger scale would perhaps demonstrate it more clearly - I might try to repeat this exercise...