Blackboard Green

Blackboard

A blackboard or a chalkboard is a reusable writing surface on which text or drawings are made with sticks of calcium sulphate or calcium carbonate, better known as chalk.

Green

Green is the color between cyan and yellow on the visible spectrum. It has 295–350 different shades. It is evoked by light which has a dominant wavelength of roughly 495–570 nm. In subtractive color systems, used in painting and color printing, it is created by a combination of yellow and cyan; in the RGB color model, used on television and computer screens, it is one of the additive primary colors, along with red and blue, which are mixed in different combinations to create all other colors. By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into chemical energy. Many creatures have adapted to their green environments by taking on a green hue themselves as camouflage. Several minerals have a green color, including the emerald, which is colored green by its chromium content.

blackboard

Noun

1. A large flat surface, finished with black slate or a similar material, that can be written upon with chalk and subsequently erased; a chalkboard.

Verb

1. To use a blackboard to assist in an informal discussion.

green

Noun

1. The color of grass and leaves; a primary additive color midway between yellow and blue which is evoked by light between roughly 495–570 nm.
2. A member of a green party; an environmentalist.

Adjective

1. Of a green hue.
2. Sickly, unwell.