Question

One group of students did an experiment to study the movement of ocean water. The steps of the experiment are listed below.

Answer 1

The lamp and the ice bag were at the same place.  
Sounds like the experiment was intended to show on a small scale ocean currents from the poles to the equator and back to the poles. The bag of ice would simulate the cold at the poles while the lamp would simulate the heat provided by the sun near the equator. With that in mind, let's look at the possible flaws and see what is likely.  
Not enough ink was added.
 * If you can see the ink, then there's enough ink. So this isn't the correct choice.  
Not enough water was taken.
 * Possibility there wasn't enough volume of water to setup a current, but not too likely since the baking dish was filled. So let's look further. 
 The dish was too small for the experiment.
 * Same as above. It might be this, but there's something more likely. 
 The lamp and the ice bag were at the same place.
 * This sounds like a winner. In the real world, the poles are cold and the equator gets more sunlight. So there's a temperature gradient. In the described setup, both the heat sink (the bag of ice) and the heat source (the lamp) were at the same location.