The beginning of the story of pencils started with a lightning. Graphite, the main material for producing pencil, was discovered in 1564 in Borrowdale in England when a lightning struck a local tree during a thunder. Local people found out that the black substance spotted at the root of the unlucky tree was different from burning ash of wood. It was soft, thus left marks everywhere. Chemistry was barely out of its infancy at the time, so people mistook it for lead, equally black but much heavier. It was soon put to use by locals in marking their sheep for ownership and calculation.

Britain turns out to be major country where mines of graphite can be detected and developed. Even so, the first pencil was invented elsewhere. As graphite is soft, it requires some form of encasement. In Italy, graphite sticks were initially wrapped in string or sheepskin for stability, becoming perhaps the very first pencil in the world. Then around 1560, an Italian couple made what are likely the first blueprints for the modern, wood-encased carpentry pencil. Their version was a flat, oval, more compact type of pencil. Their concept involved the hollowing out of a stick of juniper wood. Shortly thereafter in 1662, a superior technique was discovered by German people: two wooden halves were carved, a graphite stick inserted, and the halves then glued together – essentially the same method in use to this day. The news of the usefulness of these early pencils spread far and wide, attracting the attention of artists all over the known world.

Although graphite core in pencils is still referred to as lead, modern pencils do not contain lead as the "lead" of the pencil is actually a mix of finely ground graphite and clay powders. This mixture is important because the amount of clay content added to the graphite depends on the intended pencil hardness, and the amount of time spent on grinding the mixture determines the quality of the lead. The more clay you put in, the higher hardness the core has. Many pencils across the world, and almost all in Europe, are graded on the European system. This system of naming used B for black and H for hard: a pencil's grade reflects its composition.

Operating on the same principle as wind turbines, tidal stream generators work in water instead of air. Underwater turbines are relatively new technology, but they have major advantages over other renewable energy generators like wind and solar. Because water is about 830 times denser than air, an underwater turbine can produce vastly more electricity than a wind turbine of similar dimensions.

Tides are predictable, unlike wind and sun. They are driven by the gravitational pull of the moon and sun, meaning engineers can accurately forecast the electrical output years in advance.

Until recently, many parents and educators believed that learning two languages early in life was a disadvantage, causing confusion and slowing down cognitive development. Today, research shows that bilingualism offers significant neurological advantages throughout a person's life.