flashboard

1. (US) A board placed temporarily upon a dam, river, stream, etc. (typically within a permanent frame) to raise the water above its usual level.Examples: "A form of cheap open weir which has been commonly constructed in the West is the open wooden frame and flashboard weir."; "The railing at the upstream side also serves as a guide and a support for the manually operated hoist for the flashboard placement and removal."; "Although flashboards are designed to fail when reservoir level rises rapidly to an elevation greater than the flashboards, NPI states that most flashboard failures occur as a result of debris or ice hitting the '''flashboards."US

2. (by extension) A board that controls the flow of any material.Examples: "There exists a trapezoidal groove in the bottom of each container and a flashboard fixed in feeding system which match the groove."; "[…] a flashboard is installed on the outer side of the rear wall to adjust and open-close the seed discharge hole, with the flashboard fastened with a wedge."broadly

3. (physics) A sheet of material that is subjected to an electric pulse or flashover in order to produce plasma.Examples: "The plasma produced by the flashboard was mostly C⁺ and C⁺⁺."; "A polyethylene sheet (flashboard) is attached on the anode (aluminum), which acts as the ion source."; "The time delay between the beginning of the flashboard plasma formation and the HPM pulse generation, determines the plasma density encountered by the microwave pulse."

4. (education) An acrylic board used to display children's work in a school.

5. (education) A board for displaying language material in the classroom, used like a flashcard but potentially holding more information.Examples: "Then he comes forward, takes the flashboard V, and stands in front of the class so that all may see it ."; "The tachistoscope is a mechanical flashboard, an apparatus for testing recognition, attention, and memory, which flashes images on a screen for measured periods of time, usually from 1/100 of a second to one second."; "It is also at this level that each sentence of the experience story is put on a separate strip of paper or flashboard."

6. (historical) A device used in the 1920s for teaching typing skills which provided feedback on which key was pressed by lighting up the corresponding value.Examples: "There is a regular typewriter keyboard which is in mechanical connection with a scientifically designed, step by step "flashboard." The machine is designed to develop accurate typists through the realization of visual images."; "This flashboard also is equipped with the standard layout of letters, signs, etc., each having a white spot under it, but which is conceled by a small shutter."historical