6.Molds & Casts
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EQ: How do fossils provide a record of Earth’s geologic
history?
Learning Target: I can compare and contrast the
methods of mold and cast fossil formation.
Learning Task: I will use play-doh to create a mold and
plaster of paris to create a cast fossil. I can compare
and contrast these types of fossils.
Warm Up: Types of Fossils
Molds & Casts Lab; Fossils over Time
Molds vs. Casts – compare/contrast – in pages on iPad
Welcome! Warm Up Monday 4/7/14
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Record your response at www.goo.gl/vta7d1
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What are the 6 different types of fossils?
Amber
Mold*
Cast*
Carbon Film
Trace
Petrified
4th Quarter
Table of Contents
Title
Ice Cores
Ice Core Webquest
Fossil Notes
1
Assignment #
2
3
4
Getting into Fossil Record Webquest 5
Fossil Vocab
6
Fossils over Time (Molds vs Casts) 7
Molds & Casts
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Today we will use modeling clay and plaster of paris to
create mold and cast fossils
Materials (Groups of 3 students)
 Tray
with 8 Plastic Fossils & Fossil Guide
 1 stick of modeling clay
 1 cup of 10ml of plaster of paris
 5 ml of water
 1 craft stick
 1 piece of wax paper with masking tape
 1 sharpie to label tape with your names
Molds vs. Casts
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6.
Decide which fossil your group
would like to use. Ones that are
medium size and have texture
work best.
Break your modeling clay in ½
Google Drive:
6.Molds vs Casts
Worksheet
Work the halves of clay into 2
smooth, flat, evenly thick disks
Press your fossil into one disk
and place the other on top to
make a fossil sandwich.
Carefully peel away the clay
on one side, and then remove
the fossil.
You may have to do this several
times to make sure you have
not torn or created holes in the
Take picture of your
molds and insert into
your document.
Molds vs. Casts
6.
7.
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10.
Place the clay on your wax
paper
Your Science teacher will add
approximately 5 ml of water
to your plaster
Use the craft stick to mix the
plaster and water. It should
be the consistency of
pancake batter
Using the craft stick, pour ½
of your liquid plaster into
each mold until level with the
clay
Write your groups names and
fossil onto the wax paper and
place on the back shelf to
dry
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Complete
Worksheet Day 1
Fossils over time (Molds vs Casts)
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7
Using the chart on page 336 of your book and your
Fossil Guide, arrange the 8 fossils in your tray in
order based on the Period of time when they lived.
Copy the first 3 columns of the Geologic Time Scale
on page 336 into your notebook on page 7
Next to the respective Periods, draw the appropriate
fossil and label its name as given on the Fossil Guide
Example of what the chart you create
in your notebook might look like:
ERA
PERIOD
MILLIONS of
YEARS AGO
Cenozoic
Quaternary
1.8
Tertiary
66.4
Cretaceous
104
Jurassic
208
Triassic
245
Mesozoic
Paleoziod
Picture/Sketch of
Organism
Example of what the chart you create
in your notebook might look like:
Answer the Questions about the fossils
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2.
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10.
http://goo.gl/Vt2UvN
Which “fossil” is the oldest?
Which “fossil” is the youngest?
Describe the different Ammonites
How have the Ammonites evolved over time?
Describe the different Brachiopod shells
How have the Brachiopods shells evolved over time?
Describe the different Trilobite
How have the Trilobites evolved over time?
Why might the Trilobites be curled up?
Would these “fossils” be molds or casts?
Teacher Lab Set-up
* Fossils and Fossil Guide are in ziploc bags
Sample of students mold and cast
Used Walmart clay ($0.97) and the
scoop is 5ml Teaching Aid brand
2 scoops of plaster per cup and
About 1- 1 ½ scoops of water