The charts 
illustartes
 the improvement of tools Correct your spelling
illustrates
illustrate
of
 Change preposition
for
Stone
 Use synonyms
cut
 and how it Replace the word
cutting
affect
 in Wrong verb form
affected
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stone age
 in two different Correct your spelling
Stone Age
period
.
Change to a plural noun
periods
Overall
, in the past people Linking Words
use
 cutting tools which take out a big part Wrong verb form
used
from
 Change preposition
of
Use synonyms
Stone
 specifically Correct article usage
the Stone
middle
 side. Correct article usage
the middle
Moreover
, Linking Words
at
 the Change preposition
in
last
 Linking Words
period
 there Add a comma
period,
is
 a significant improvement Wrong verb form
was
of
 cutting tools, Change preposition
in
while
 Linking Words
side
 Correct article usage
the side
view
 Use synonyms
thiner
 than in Add a missing verb
was thiner
first
 period.
Change the article
the first
In a
 one million and four Change preposition
A
hounderd
 Correct your spelling
hundred
years
 ago Use synonyms
Stone
 shapes in cutting Use synonyms
was
 semi tringular, which means in both Correct subject-verb agreement
were
front
 and back Correct article usage
the front
Use synonyms
view
 there shape was thin Fix the agreement mistake
views
in
 first 5 cm Change preposition
at
then
 got wider.
Linking Words
In eight
 Change preposition
Eight
hounderd
 Correct your spelling
hundred
years
 ago there was Use synonyms
Correct article usage
a different
different
 in cutting Replace the word
difference
Stone
, were Use synonyms
both
 front and back Correct determiner usage
the
Use synonyms
view
 bigger than Fix the agreement mistake
views
Stone
 Use synonyms
in 
1.4 million Change preposition
apply
years
 ago , but there side Use synonyms
view
 was thinner than Use synonyms
it 
Correct pronoun usage
apply
in 
1.4 Change preposition
apply
millions
 Change to singular
million
years
 ago.Use synonyms