Does acquisition of hypothetical conditional sentences contribute to understanding the principles of scientific enquiry?

• Conditional sentence comprehension predicts early understanding of hypothesis testing. • Conditional sentence comprehension predicts awareness of control of variables strategy. • Relationships between grammar and science tests are independent of reasoning ability. • Passing science reasoning is associated with high scores on national science test. Principles of scientific investigation are often described using hypothetical "if" sentences. The current study explored whether the acquisition of such language is related to earlier understanding of scientific principles, specifically hypothesis testing and control of variables strategy. 98 children 8–9 years of age were tested individually on conditional sentence comprehension, repetition and scientific reasoning. Reasoning ability was tested with groups of children. Children who failed the scientific reasoning tests were re-administered the test/s they failed and grammar tests two years later (age 10–11). Good understanding of hypothetical conditional sentences at age 8–9 predicted showing understanding of hypothesis testing early (age 8–9) rather than late (age 10–11) and predicted passing control of variables strategy test by age 10–11, controlling for non-verbal and verbal reasoning ability. Comprehension of complex conditional sentences might be helping children with understanding the underlying principles of scientific investigation. [ABSTRACT FROM AUTHOR]