Thinking aloud about NEW AND OLD BALLS and ramps

Bemilies, et al.

University of Kentucky--Lexington, KY

ABSTRACT

INTRODUCTION

Scientists use many methods of investigation, but the classical method is experimentation. In a simple experiment, the researcher’s goal is to determine whether a variable of interest (the “focal variable”) has a causal influence on the phenomenon under study. In order to make this determination, the experimenter must design an experiment that meets two basic criteria. First, the focal variable must be manipulated. Second, all other variables must be kept constant. Our research is concerned with teaching this “control of variables strategy” (CVS) to 4th-graders.

The purpose of the present study was to apply prior work on instruction methodology (e.g., Chen and Klahr, 1999; Toth, Klahr and Chen, 2000) to a classroom setting. The present study addressed three main questions. (1) What are the relative contributions of direct instruction (i.e., interactive lecture developing the logic of CVS) and discovery (i.e., opportunity to actually conduct experiments) to learning CVS? (2) Are any immediate gains in learning of CVS maintained across the school year? And (3) Do our findings depend on the school environment (i.e., school achievement level)?

RESULTS

DISCUSSIONMETHOD

Participants Participants were 56 children in 4th grade gathered from extended school

programs. Children completed the procedure in one session.

Design

The design was a 2 (think aloud) x 2 (time of test) mixed factors design. The levels of think aloud were (1) think aloud: students were instructed to speak aloud about their decisions and (2) silent: children were worked on their own without explicit instruction to speak aloud. The levels of time of test were (1) pretest and (2) posttest.

Materials

Paper and Pencil CVS tests- This test included five items from each of three different domains (e.g.,

baking cookies, growing plants). Each item compared two experimental conditions that could vary on any combination of three variables.

- For example, some of the items on one test version investigated three variables that might influence how quickly plants grow (i.e., whether the plants received plant food, whether they received direct or indirect sunlight, and whether the plants got a lot of water or a little water).

- There were three versions of the CVS test; each student received a pre-CVS and post-CVS test.

Ramps- We used ramps as our domain for demonstrating and testing (see the photo

below). The apparatus consisted of two, 4-foot long ramps constructed of plastic. Additionally, there were four variables, each with two levels, that could be manipulated on the ramps: a rough or smooth surface, a high or low steepness, the long or short length of run, and a new or used golf ball.

Procedure

Students completed the pre-CVS test.

Students were introduced to the ramps and variables and designed and ran experiments on each of the four variables to determine if each variable impacted the distance the ball rolled down the ramp.

Students received the teaching protocol. A trained student administered the teaching protocol, which provided confounded “bad” experiments and provided corrected “good” experiments, with explanations of what made an experiment “good” or “bad”. Students were encouraged to participate during the teaching. The teaching protocol concluded with an explicit statement of the CVS.

After the teaching, students completed a post-ramps packet, where they were instructed to apply their learning about CVS as they designed and ran experiments on the four variables. Students in the think aloud condition were instructed to speak out loud about their thought processes as they designed and ran their experiments. Students in the silent condition did not receive this instruction.

Students completed the post-CVS test. Students in the think aloud condition were instructed to continue describing their decision processes aloud. Students in the silent condition did not receive this instruction.