Sentence 1: Ron was busy building a wooden shelf in his workshop. 
 Sentence 3: With a saw he then cut up the pieces 
 Sentence 4:  Ron used mostly screws but some glue to assemble it 
 Sentence 5:  He set the finished shelf aside to let the glue dry 
 Option 1: he did not have a ruler to measure the wood. 
 Option 2: He measured out the wood with a ruler and pencil.