2. Before showing this clip you could divide up the students into groups to test floatability of different objects in a variety of fluids. They would have to weigh the objects, figure out each object's density and predict sinking or floating, given the density of the fluid. Doing this in fresh water would be a good start. Students could use objects such as wood, paper clip, nails, plastic, pebbles, high-bounce balls, and small steel or iron cubes. Then you could show the clip and have the students try and figure out why the steel ship did not sink initially. They could start by finding the dimensions of the Titanic to look for its density. Then students might reason because it is in salt water, because it has an engine, it's unsinkable. Have them research other answers. In reality it is because the ship contains lots of air, which has a much smaller density than water. When the air and the steel are averaged together the ship can float. However, when water begins to fill in the ship through holes, the ship becomes denser and it sinks.
3. As an assessment you could show this clip and have students describe what is causing the ship to sink. They would have to use all their knowledge of Archimedes law to help them figure out what is happening.