Successfully

Son reading a book .. "It took them many months but they suss-s-k- ..."
Son: What's this word mumma? 
Mom: Successfully
Son: Say it again! It's difficult and I don't even know where is 'k' and where is 's' sound 😦
Mom: successfully .. break it into parts and try! 
Son: sus-ek-fully
Mom: No, suk-ses-fully
Son: su-sesk-fully
Mom: No, it is suk-ses-fully. Like how you say suck
Son: suk-sesk-fully
Mom: No 'k' sound later. Just suk-ses-fully
Son: suk-ses-fully .. suk-ses-fully
Mom: You got it! Now, read the complete sentence! 👍
Son: "It took them many months but they su-sesk-fully crossed the.... "
Mom: 😥 No success!