Science for seven- to nine-year-olds. How the sound a piece of string makes when it's plucked varies with its length and tension.
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Science for seven- to nine-year-olds. How the sound a piece of string makes when it's plucked varies with its length and tension.
BBC Two is a lively channel of depth and substance, carrying a range of knowledge-building programming complemented by great drama, comedy and arts.
