I don't understand the early atmosphere topic and the convection current, tectonic plates that topic
can somebody please explain it to me
Early Earth was mainly volcanoes, giving off gas and steam. As the gas built up, it began to block out the sun's light and cooling the earth. The cooling allowed water vapour to condense and for oceans. Oceans absorb CO2 as well as producing oxygen through photosynthesis of green plants. A build up of oxygen created the Ozone layer, allowing more complex organisms like humans to evolve.
The Earth's crust is split into tectonic plates, which sit on the mantle. Radioactive decay in the mantle cause convection currents to occur in the mantle (due to less dense magma rising - not needed). The movement of magma causes the tectonic plates to move.