1. Comparing two activities' effectiveness improving reasoning with multiple-variable information Rebecca Rosenblatt and James Perrone
Summary of Reported Findings
Students make similar errors on more complex pictorial experimental trials
1. Summarize studies showing large differences in student ability to use, and reason with, certain data in graph or pictorial form. A majority of the errors are consistent with failure to control variables or illogical reasoning from the data.
2. Report on the effectiveness of two different one-hour group activities designed to improve student understanding. Both activities improved student ability to draw conclusions and answer questions about the data in graph or pictorial form.
Controlled & Changed Variable – e.g. left set of trials & question about mass
66% correct
Controlled & Unchanged Variable – left set of trials & about surface area or floor material
42% correct
Not controlled & Changed Variable – right set of trials & about floor material or mass
55% correct
Not controlled & Unchanged Variable – right set of trials & about surface area
44% correct
Scores depend strongly on the variable asked about
Controlled & Changed Variable – e.g. left set of trials & question about light bulb type
52% correct
Controlled & Unchanged Variable – left set of trials & about wire color or battery number
38% correct
Not controlled & Changed Variable – right set of trials & about battery # or light bulb type
42% correct
Not controlled & Unchanged Variable – right set of trials & about wire color
35% correct
Directly Affected Relationships Students Score 85% or better.
Does Not Affect Relationship Students Score 70% - 85%.
Unchanged Variable Relationships Students Score 30% - 40% only
Not controlled Variables Relationships Students Scores 30% - 50% only
Tutorial on logical reasoning
Laboratory on control of variables reasoning
DA: How does X effect Y? How does length affect Period?
Individual – reading a one page explanation, with included examples, of what it means for variable A to affect (or not affect) variable B
Small group completion of a worksheet with the following tasks
From a pendulum data table students made substantiated
cause/effect conclusions about the variables
Student Dialogue Questions focused on common logical issues
Created graphs from some of the data table and made rules about how the data should look when a variable affects and does not affect another variable
Individual pre-lab – design a lab to find mass and surface area’s effect on the static friction.
Instructor lead demonstrations involving comparing data from two pendulums and what conclusions can be made about mass, length, release angle’s effect on the period. Several different comparison pendulums were used. Emphasis was placed on the need for control of variables while experimenting.
Small group execution of the friction lab from students’ designs.
Groups summarized their findings with graphs and presented their results to the whole lab via white boards
Unchanged: How does Z effect Y? How does mass affect Period?
DA/DN: How does X effect Y? How does mass affect Period?
Unchanged: How does Z effect Y? How does length affect Period?
Conclusions
Type
Variable X
Graphs/Pics
Friction
Light bulbs
Score
Gain
Controlled
Changed
91% 6%
89%
23%
39%
Unchanged
50% 8%
60%
18%
61%
13%
Uncontrolled
64%
11%
55% 0%
53%
21%
--NA--
65%
19%
67%
32%
** Reported are the correct percentages post instruction with an additional activity. The gain is the improvement on each topic compared to traditional instruction. Since the two activities posttest scores and improvements were not significantly different they are averaged here.
While students are quite good at the directly affect variable relationships, they do not understand how to deal with variables that were unchanged or when the experiment was not controlled, i.e. more than one variable is changed at once.
A majority of the errors made by students are consistent with failure to control variables and incorrect logical reasoning.
We created two PER based instructional activities designed for lab or recitation. Both activities moderately improved students’ understanding. Because one focused on control of variables and the other on logic this is additional evidence that both skills are needed to correctly work with these questions.
In addition, because skills on the untaught topic of light bulbs also increased this is evidence that students are abstracting the skills of control of variables and logical reasoning with data.
Not controlled: How does mass (length) effect Period?
Students struggle with questions about a variable which was unchanged in the graph and/or pictorial data and with data that is not controlled, i.e. too many variables are changed at once.
Students make persistent and consistent logical mistakes concluding Since B changes and A does not, then A must not affect/change B or Since A changed and B changed, A must affect B.