National Geographic's Adventure on the Titanic; History.com also has fantastic interactives for exploring the history of the RMS Titanic.
Titanic: Fortune & Fate - Catalogue from The Mariners' Museum Exhibition was another great read. It's a treasure trove of Titanic artifacts and memorabilia, including "letters, momentos, and personal effects from those who sailed on the lost ship". We also recommend All Stations! Distress! by Don Brown, an excellent illustrated children's book that captures the essence of the Titanic disaster. On top of all these great reads, we also had fun doing a timeline, a crossword puzzle, and a quiz on all we've learnt.
"I cannot imagin any condition which would cause a ship to flounder. I cannot conceive of any vital disaster happening to this vessel. Modern shipbuilding has gone beyond that."
- Captain Edward Smith of the Titanic