My two youngest girls both love puzzles, still do. DD4 had a strange way on putting them together too. both started at about 18 months , but the younger one would put random pieces of the puzzle in, no order at all, she would just pick up a piece put it down and thats where the piece would go. I have video of it and it still looks strange to me. I think they all just go at thier own pace whatever that may be. For example my girls wouldn't even look at lego's had no ideal what to do with them, then recently we went to legoland and now they've brought all the lego's out they received for Christmas's and birthday's and now I have masterpeices around the house. LOL