Per DL, spoon/puna takes "ke" (dictionary verifies this) but here itʻs "ka". (Ka puna is spring of water). Edit: Duo is now using ke for puna. 3/3/19

By Wehewehe.org, "ke puna" is the correct use of the article. The word for fork, ‘ō begins with an okina, not an "o." The proper article for this word is "ka," as in "ka ‘ō." I believe DL got this one reversed, which is unfortunate. Imagine trying to learn English with the sentence "a egg and an bird." I wrote "Ke puna a me ka ‘ō" and was marked incorrect.

Thank you for the information posted.