Before
Goodall
?
s
discovery
,
scientists
____________________
that
Humans
were
the
only
creatures
on
earth
to
use
and
make
tools
.
Goodall
was
able
to
correct
this
assumption
.
One
day
,
as
she
____________________
a
chimp
,
she
saw
that
he
____________________
a
piece
of
straw
as
a
tool
.