Studies of the effects of programming tended to vary between the wave and
swell levels. Some attempted to hold content as fixed as possible, at least as
reflected in the measurement of outcomes, for example, algebra in the case of
Hatfield & Kieren (1972). However, the underlying activity of writing programs
actually offers a radically new experience for the student-such as
building a computational model to solve a problem or creating a program that
draws novel geometric objects (Clements & Battista, 1989; Clements & Battista,
1990; Noss, 1987; Olive, 1991). These activities were usually not at all
present in the existing curriculum. Hence the "content" in terms of the mental
activity of the student really cannot be held fixed.