A large number of American elementary school students are now studying science using the hands-on inquiry curricula developed in the 1990s: Insights; Full Option Science System (FOSS); and Science and Technology for Children (STC). A goal of these programs, echoed in the National Science Education Standards, is that children should gain abilities to do scientific inquiry and understanding about scientific inquiry. We have studied the degree to which students can do inquiries by using four hands-on performance assessments, which required one or three class periods. To be fair, the assessments avoided content that is studied in depth in the hands-on programs. For a sample of about 1000 fifth grade students, we compared the performance of students in hands-on curricula with an equal number of students with textbook curricula. The students were from 41 classrooms in nine school districts. The results show little or no curricular effect. There was a strong dependence on students' cognitive ability, as measured with a standard multiple-choice instrument. There was no significant difference between boys and girls. Also, there was no difference on a multiple-choice test, which used items released from the Trends in International Mathematics and Science Study (TIMSS). It is not completely clear whether the lack of difference on the performance assessments was a consequence of the assessments, the curricula, and/or the teaching.