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I had six classes and each conducted their own
experiment on crystals. Most of the classes
designed and conducted their research investigation
on the effects of heat or flame on crystal. The
remainder of this RIP-inquiry description will focus
on the inquiry conducted by one of these classes.
This was the first time that my students are to be
exposed to the process of scientific inquiry in my
classroom and most likely in any of their previous classes. Thus, in order to cover all of the
components of the inquiry process, I expected the
extended guided inquiry to take more than just a few
days. In addition to covering the components of
scientific inquiry, this guided inquiry was designed to
lead students into the study of the characteristics of
the three main types of rocks (a benchmark for the
eight grade science Hawaii Content and Performance
Standards).
Crystals or broken crystals of different kinds
of minerals, or broken pieces of rocks are what
mostly make up rocks. So scientific investigations
focusing on crystals can easily include in their
background information section earth science content
about rocks and minerals. The three types of rocks
can generally be identified by how they are made,
composition and texture.
igneous
  
The surface of the Earth (crust) is mostly made of
igneous rocks-solids made out of crystal which form
directly from the cooling of magma. The formation of
these rocks involves an exothermic process in which
heat is lost. There is also a change from the liquid to
the solid state during the formation of igneous rock.
Some igneous rocks cool rapidly and others slowly,
depending upon how they were formed. Rocks that
typically have a fine grain and appear glassy cooled
rapidly during their formation, while those with large
grainy surface features cooled slowly.
Observing Crystals (Day 1)
I began the unit by providing my students the
opportunity to observe and compare test tubes containing
two different types of crystals: one containing crystals made
from saturated Hawaiian table salt the other containing
crystals made from Epsom salt. The students worked in
groups to perform this task.
Observations were recorded and shared among the
participants within each research group with the goal of
evaluated each one as "subjective" or "objective."
Observations of crystals by my students
(Click on table to enlarge)
Background Information (Day 3)
In class, students shared the background materials
they found for their homework assignment. Students spent
the remainder of the time on Day 3 looking up more
information about crystals in their textbooks and other
resources found in the school library.
Students researching background information at the library
The information gathered by the students was shared,
explained, and written on chart paper for all to see. This
resulted in a general class background information section
for the investigation.
Writing down the information found in background resources
Writing down the information found in background resources
Designing the Study: the Method (Day 5)
Together as a class, the students designed their
scientific investigation, planning what subjects and
materials they would use and the procedures they
would follow. As the students discussed these
components of their study, their thoughts were written
on chart paper at the front of the classroom.
The Subjects
The subjects in this scientific investigation were
salt, sugar, and alum crystals. These crystals were
grown and harvested by the students using the materials
and procedure described below. The crystals that were
used to test the hypothesis in the actual investigation
were then randomly selected using a random numbers table.
The Materials
The materials used for this scientific investigation
are listed below.
In addition, we used a pan balance and graduated cylinders
for massing and measuring chemicals.
Students volunteered to bring the materials necessary
to conduct the investigation to school the next day.
Preparation of Solutions for Crystal Growth (Day 6)
The supersaturated solutions for growing crystals were
prepared following the procedure developed by the students.
This preparation allowed for crystal growth within 2-4 weeks.
Waiting for the water to boil
Massing the chemicals
Using precise measuring tools
Adding alum to the boiling water
Stirring alum into the boiling water to make a super-
saturated solution
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sedimentary
  
  
Sedimentary rocks are composed of gathering together
of small pieces of pre-existing rocks, dissolved minerals
from the ocean left behind after evaporation, or calcium
(from animal shells or teeth) or other minerals related to
organic processes that come together. Weathering,
decaying of dead organisms, or dissolving from exposure
to flowing water are all processes that contribute to the
breakdown of the original rocks and organic structures that
compose sedimentary rocks. These rocks can usually be
identified by their being made up of many small pieces of
rocks that appear to be cemented together or by their
layered look.
metamorphic
  
 
When the minerals making up any type of rock become
unstable because of environmental forces such as pressure
and/or temperature changes, the rocks themselves change
and are considered to be "metamorphic." These rocks are
usually formed deep inside the earth. Many, but not all, of
these rocks have a sheet-like structure or appear to be
made of stacked plates.
Formulating & Posing a Research Question (Day 2)
Students brainstormed about questions they had about
crystals. The questions were listed on chart paper in the
front of the classroom for all to see. The first step was to
eliminate questions that were not practical (could not lead
to a testable hypothesis and those that were useful (could
lead to a testable hypothesis). Through discussion the
class evaluated each question as good (useable) or bad
(not useable).
The class decided that they would vote on which
question they liked the most and that became their
research question that they they would try to answer
through a scientific investigation. The most popular question
was, What happens to crystals when they're heated?
Student-formulated research questions and the results of
voting (circled in blue)
Students voting for their favorite research question
At the end of the second day of the inquiry, I assigned the
students the homework task of researching information on
crystals.
Constructing the Hypothesis (Day 4)
Using the research question and background information from the previous day, the students worked in groups to answer
the question by writing a testable hypothesis in an "If...then...
because" format. Each student-generated hypothesis included
the conditions that would be used to test it, the predicted
results, and the rationale underlying the prediction.
 Constructing the groups' hypotheses
Each group of students then listed only the conditions that
would be used to test their hypothesis on the front board so that
these could be examined by the entire class. This way the class
could see all of the experiments that they could choose from for
the class investigation. Voting again took place so that the
students could determine the class investigation that was most
popular. After the winning experiment was determined, all
student were asked to write in their composition books their own
prediction and rationale for that experiment. Each of my six
classes chose a hypothesis. The hypothesis adopted by my
period 6 class was:
The hypothesis to be tested
The Color Scale
I wanted the students to collect both qualitative and
quantitative data for testing their hypothesis. I guided them in
the construction of a scale for crystal color and consistency
changes that would involve both qualitative and quantitative
data. The scale was constructed by the class using background
information and past experiences with the consequences of
applying heat to various substances. They were able to put
their observations in the form of descriptive statements
regarding the heating of objects into a table (see Table 1
below). We then assigned a number to each object to reflect
the amount of change resulting from exposure to a flame. This
became our rating scale (Table 1).
The scale was arranged on a continuum from least (No Change)
to most (Catches Fire or Melts) change. Although one could
argue that these numbers represented ordinal rather than
interval or ratio level data, they permitted my students the
opportunity to perform data summarizing and analysis using
descriptive statistics.
The Procedure
Collecting & Drying the Crystals (Day 7)
The solutions were strained through the coffee filters and
allowed to dry overnight. Crystals were then randomly selected
for the heat study.
Close-up of the alum crystals grown by the students
Close-up of the sugar crystals grown by the students
Close-up of the salt crystals grown by the students
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