"This child is big."
Translation:To dziecko jest duże.
can someone explain the difference between duże and duża? I am having a lot of trouble getting the spelling changes between words in the context of the sentences.
Gender. Every adjective has to match the gender of the noun/pronoun it describes.
"duże" is neuter (or 'not masculine-personal plural'). The word "dziecko" is neuter, so it "duże dziecko". As we mentioned 'not masculine-personal plural', "dzieci" (children) belong to this plural, so it's "duże dzieci".
"duża" is feminine. "duża książka" = "a big book".
"duży" is masculine. "duży kot" = "a big cat".
And finally there's 'masculine-personal plural', used for 'groups with at least one man'. "duzi ludzie" = "big people". This form is usually quite different from the other ones.