In   this   activity,   students   can   model   how   trace   fossils   form,   by   creating   a   special   dough   and   making   impressions   in   it   with   various   materials.
After   it   dries,   each   student   will   have   their   very   own   model   trace   fossil   to   take   home!
Materials (enough for a classroom of up to 20-25 students)
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1 cup salt
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3 cups flour
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1 cup brewed coffee (cold)
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2 cups used coffee grounds
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Wax
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Mixing
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Mixing
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Measuring
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Objects to make fossil impressions (ex: shells, plastic animal models for footprints or skin impressions, stiff leaves, twigs, etc)
Directions
Teacher   can   either   opt   to   create   the   dough   before   hand,   or   create   it   with   the   class.
To   make   the   dough,   mix   together   1   cup   salt,   3   cups   flour,   1   cup   cold   brewed   coffee,   and   2   cups   used   coffee   grounds   in   a   mixing   bowl.
Stir   well   until   the   mixture   is   smooth.
Extra   flour   may   be   used   if   the   consistency   is   too   drippy.
Spread   dough   out   on   wax   paper,   flatten   with   hands,   and   break   off   enough   pieces   for   each   student.
Make   sure   each   student   has   their   own   piece   of   wax   paper   to
work   on.
Once   each   student   has   a   piece,   have   them   flatten   it   onto   their   wax   paper   to   about   the   thickness   of   a   chocolate   chip   cookie   (1/4 ‐ 1/2   inch   thick).
Then,   they   can   take   the   object   of   their   choosing,   and   push   it   into   the   dough.
Remove   object   carefully   and   slowly.
Then,   leave   the   dough   with   the   impression   to   dry.
Drying   may   take
2 ‐ 5   days,   depending   on   humidity   levels.
Oven   baking   is   discouraged,   as   it   often
results   in   cracking   of   the   dough.

What This Illustrates
This   is   how   trace   fossils   form!
Trace   fossils   are   not   the   same   as   bone   fossils,   because   the   actual   object   does   not   remain   as   the   fossil.
Something   (like   a   foot,   or   skin,   or   a   feather,   or   a   leaf,   or   a   bug,   or   a   shell…)   gets   pushed   into   a   soft   substance   (like   mud)   and   creates   an   impression,   and   then   the   substance   hardens   up.
If   it   undergoes   enough   pressure   by   being   buried   in   the   Earth,   it   can   be   turned   into   rock   and   becomes   a   fossil   for   paleontologists   to   find   millions   of   years   later.