Under normal instructional circumstances, some youngsters learn programming in BASIC or LOGO much better than others. Clinical investigations of novice programmers suggest that this happens in part because different students bring different patterns of learning to the programming context. Many students disengage from the task whenever trouble occurs, neglect to track closely what their programs do by reading back the code as they write it, try to repair buggy programs by haphazardly tinkering with the code, or have difficulty breaking problems down into parts suitable for separate chunks of code. Such problems interfere with students making the best of their own learning capabilities: students often invent programming plans that go beyond what they have been taught directly. Instruction designed to foster better learning practices could help students to acquire a repertoire of programming skills, perhaps with spinoffs having to do with “learning to learn.”

We show that arylpalladium(II) reagents linked to biotin and indocyanine dye residues can be prepared by decarboxylative palladation of appropriately substituted electron-rich benzoic acid derivatives. When prepared under the conditions described, these organometallic intermediates are tolerant of air and water, can be stored for several months in solution in dimethylsulfoxide, and permit biotin- and indocyanine dye-labeling of functionally complex olefinic substrates in water by Heck-type coupling reactions.

This article examines unifying factors among diverse problems of understanding in several fields. Certain misunderstandings in science, mathematics, and computer programming display strong structural analogies with one another. Even within one of these domains, however, not all misunderstandings are structurally similar. To explain the commonality and variety, four levels of knowledge are posited: (a) content, (b) problem-solving, (c) epistemic, and (d) inquiry. Through analysis of several examples, it is argued that misunderstandings have causes at multiple levels, with highly domain-specific causes predominant at the "content" level and somewhat more general causes at the other levels. The authors note that education characteristically neglects all but the content level, describe successful interventions at all levels, and urge more attention in education to integration across the levels. Cornell University, July 26-29, 1987. We thank John Clement, Jack Lochhead, and Carlos Vasco for helpful conversations based on an earlier draft of this paper.

[reaction: see text] When hexa-1,5-dien-3-ol is protected with bulky groups, a regioselective cross-metathesis reaction can take place at the C5-C6 double bond.