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ERIC Number: EJ1136570
Record Type: Journal
Publication Date: 2017-Apr
Pages: 13
Abstractor: As Provided
ISSN: ISSN-0022-0663
Conceptual Knowledge of Decimal Arithmetic
Lortie-Forgues, Hugues; Siegler, Robert S.
Journal of Educational Psychology, v109 n3 p374-386 Apr 2017
In 2 studies (Ns = 55 and 54), the authors examined a basic form of conceptual understanding of rational number arithmetic, the direction of effect of decimal arithmetic operations, at a level of detail useful for informing instruction. Middle school students were presented tasks examining knowledge of the direction of effects (e.g., "True or false: 0.77 * 0.63 > 0.77"), knowledge of decimal magnitudes, and knowledge of decimal arithmetic procedures. Their confidence in their direction of effect judgments was also assessed. The authors found (a) most students incorrectly predicted the direction of effect of multiplication and division with decimals below 1; (b) this pattern held for students who accurately compared the magnitudes of individual decimals and correctly executed decimal arithmetic operations; (c) explanations of direction of effect judgments that cited both the arithmetic operation and the numbers' magnitudes were strongly associated with accurate judgments; and (d) judgments were more accurate when multiplication problems involved a whole number and a decimal below 1 than with 2 decimals below 1. Implications of the findings for instruction are discussed. [For the Grantee Submission, see ED569126.]
American Psychological Association. Journals Department, 750 First Street NE, Washington, DC 20002. Tel: 800-374-2721; Tel: 202-336-5510; Fax: 202-336-5502; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Research
Education Level: Middle Schools; Secondary Education; Junior High Schools
Audience: N/A
Language: English
Sponsor: Institute of Education Sciences (ED)
Authoring Institution: N/A
Identifiers - Location: Pennsylvania (Pittsburgh)
IES Funded: Yes
Grant or Contract Numbers: R305A150262; R324C100004