Academy Curricular Exchange
Columbia Education Center
Science



TITLE:   Mixtures 

AUTHOR:   Gary L. Wiggins; Cascade Elementary School, WA

GRADE LEVEL/SUBJECT:    3-5   Science

OVERVIEW:  Variables affecting the rate of the dissolving of
a substance (solute) in water (solvent) are discussed and
observed through experimentation.

PURPOSE:  Students will be able to test/experiment with
several variables, against a control, to observe the different rates
that a solute (sugar) dissolves in a solvent (water) to form a
solution.

OBJECTIVES:
1)  Students will observe that movement of the solute in the solvent
increases the rate of dissolving, as compared to the control.
2)  Students will observe that the solute, when broken into smaller
parts, will dissolve in the solvent faster, as compared to the
control.

RESOURCES/MATERIALS:For each group: piece of paper, three clear
drinking glasses, one spoon, paper towel, three sugar cubes.

ACTIVITIES AND PROCEDURES:
Students form groups of three.  Each member has a job--recorder,
"go-for," and taskmaster.

First, the recorder folds a piece of paper in half, from top to bottom.
The top half is used to record predictions, the bottom half is to
record observations.  He then separates each half into thirds (rows).
The recorder folds the paper in half, left to right, then in half once
again (fourths) to obtain four columns.  He writes the members'
names in the first column, in both top and bottom halves, one
name per row.  At the top of the second column he writes "control."
At the top of the third column he writes "with motion." Finally, at
the top of the fourth column he may write "smaller pieces." 

Secondly, the "go-for" obtains three clear glasses half-full of water
of the same temperature, three sugar cubes, spoon, and paper
towel. Taskmaster makes sure all procedures are followed.  He may
do everything himself or delegate jobs to others.  He is responsible
for quieting group members during teacher instruction. 

Now, each group has before it a control (glass with sugar cube), a
motion glass (glass with sugar cube and spoon), and a small piece
glass (glass with broken sugar cube). Each student should make a
quick prediction as to what might happen when sugar is placed in
each glass simultaneously.  The emphasis should be on the order to
which glass will have a solution first, second, and third.  The
recorder should record these predictions.  At the same time, the
sugar should be placed in the glasses and the movement glass should
have constant stirring until a clear solution is obtained.  All should
observe and the recorder may then list the observations of each
member. Of course, there are other variables that students may want
to try: heat, heat and movement, pieces and movement, etc.

TYING IT ALL TOGETHER:
Students should be able to find ways to obtain mixtures more
rapidly from the exposure to the variables discussed and observed in
this lesson:  from mixing frozen orange juice for breakfast, melting
things for mixtures in cooking (butter), stirring ingredients for
batters, to putting out a campfire (stirring the ashes with water).
The students may think of other everyday situations with mixtures
that may use the experimented variables.


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John Kurilecjmk@ofcn.org