Enhanced Clay Extraction
Allows you to collect 2 clay per click instead of 1. And if you're lucky 2 flint instead of 1.
Teaching
This skill was obtained from the
Mysterious Altar located in Sinai. If the behavior is the same as the other skills, the Tier 1 teacher can teach up to 8 people. These Tier 2 teachers can teach an unknown (unlimited?) number of people. Those people taught by Tier 2 are considered Tier 3 and can only teach one person, and if they do so, they lose the skill and cannot relearn it. Anyone taught by a Tier 3 is also considered a Tier 3. As with the other Enhanced skills, this skill is teachable in two lessons.
Clay Effects
Other than doubling clay, this skill seems to have no point. It also causes Raeli Ovens to produce broken tiles (more info is needed).
Currently investigating; my notes are here. It only takes one scoop of clay with ECE to cause tiles to break! -- Japto
UPDATE: The ovens do heal after a period of time. It isn't clear if this is tied to when the tiles were dredged or when the baking process begins.