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I would also suggest the following changes be made in our state standards:

Grade 3: 2a: "sunlight can be blocked to create shadows" should be replaced by "light sources can be blocked to create shadows." Students can easily make shadows using room lighting or flashlights.

Grade 3, 4d: "the Earth is one of several planets that orbit the sun" should be replaced by "the Earth is one of nine planets that orbit the sun." If students can count to nine, why not use the correct number instead of the ambiguous 'several.'

Grade 4, 4b: "solar energy reaches Earth through radiation, mostly in the form of visible light" should be replaced by " … some of it in the form of visible light." The statement as currently written is wrong. For an excellent discussion of this point, see the American Journal of Physics, volume 67, p. 946 (1999).

Grade 7, 6c: "light travels in straight lines except when the medium it travels through changes." This statement is wrong. At normal incidence, light will travel in a straight line as it enters a material with a different index of refraction. Light will also travel in a straight line at off-normal incidence if the indices of refraction of the different media are the same.

Grade 7, 6f: "light interacts with matter by transmission (including refraction), absorption, or scattering (including reflection)" should be replaced by "light can be reflected, transmitted, or absorbed by matter." When written in this way, it is a statement of energy conservation. Scattering includes both reflection and transmission and should properly refer to both, not just reflection.

Grade 8, 1b: "The speed of an object along the path traveled can vary." Either delete this awkwardly written sentence or replace it with the simpler, "The speed can vary."

Grade 8, 7c: "substances can be classified by their properties, including melting temperature, density, hardness, heat, and electrical conductivity." Delete the word heat. Heat is not a property of a substance. If the authors meant thermal conductivity, they should use thermal conductivity.