This is the 10308th most frequent Polish word.
chodnikami
"Chodnikami" means "sidewalks" or "walkways" in the instrumental plural form in Polish.
In this sentence, 'chodnikami' is used in the instrumental plural form of 'chodnik', referring to sidewalks as the medium through which the children are running.
Dzieci biegały chodnikami, bawiąc się w berka.
Children ran on the sidewalks, playing tag.
Here, 'chodniki' is in its nominative plural form, referring to sidewalks as the direct subject of investment.
Miasto zainwestowało w nowe chodniki, które teraz są bardzo wygodne.
The city invested in new sidewalks, which are now very comfortable.
In this example, 'chodnikami' is again instrumental plural, indicating the paths (sidewalks) used for walking.