I've never taken this course but i can try to help with the feedback
It looks like the assignment was to try experimenting with different shutter speeds and apertures to see the effect.
In your first photo the main subject is blurred because of the low shutter speed at 60. However the stationary background is relatively sharp because of the aperture of 18. The larger this number the more depth of field (objects in the picture further to the back or closer to the camera than the main subject) will be in focus.
In your second picture you nailed it
with the higher shutter speed of 500 you were able to completely freeze the action of your main subject, while letting the background of the picture fade more into the background with the lower aperture of 6.8.
You will find in general if you keep your ISO fixed as in these photos that there will be a interplay between aperture/depth of field and shutter speed. As one goes up the other will go down to equal the two out
Great job, i think its especially good because it looks as though you were taking the photos under overcast sky which can be more challenging
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