I found some more episodes showing shorts. Pics 1, 2+4 are from s4e7 (1983) Inequality: Kids vs. adults. Looks like a girl in pic 4 in dark blue shorts but not sure as there are also longhaired boys.
Pic 3 is from Looking Cool (season 9, 1990) looks like short, yellow Basketball shorts. Unknown if shiny. Brief views and shirts are long.
There are probably more scenes, unfortunately some episodes got deleted.
Main entry, rating 8
Today, another episode of Koen Kampioen.