Mid ocean ridges which contribute to the process of seafloor spreading Form as a result of two tectonic plates moving apart (or diverge). As the plates move apart, a crack is formed in the rock between the plates.
Magma rises from beneath and flows up through the crack and spreads out over the crack where it cools as it meets the sea water and solidifies adding to the edges of the sideways moving plates.
A long chain of mountains called an oceanic ridge is formed as magma continues to pile up along the crack.
Your experiment tests whether your prediction is accurate and thus your hypothesis is supported or not. It is important for your experiment to be a fair test.