By the way. The sentences seem long because your box is not long enough.

Thesis:If you do not know the impact of the Industrial revolution, you will not understand anything in this essay. This topic is very good to study because you know about the different views. The Industrial Revolution changed Britain and if it did not happen Britain would not have great technological advances of the 20th century.
II. BODY PARAGRAPH 1:

Opening Sentence:The Industrial Revolution was a period from the eighteenth to the nineteenth century where major changes happened.

Detail: in agriculture, manufacturing, mining and transport had a massive effect on the social, economic and cultural conditions starting in the United Kingdom.

Transition/Opening Sentence:____Before the Industrial Revolution Britain was a different place to what it is today.

Detail 1:_ It was very hard to keep in touch with people in other parts of the country. News was spread by travellers or through messengers goods.

Detail 2:__It was hard to move around, there were no cars, buses or aeroplanes

Detail 3:. Food was produced locally, agriculture could provide for but a few towns. Clothing was also made locally.

V. BODY PARAGRAPH IV:

Transition/Opening Sentence:During the Industrial revolution, changes were made but not every area changed
Detail 1:As factories spread rapidly the owners of mills, mines and other forms of industry needed large numbers of workers and they didn't want to have to pay them a high wage

Detail 2:_Children were the ideal employees therefore! They were cheap, weren't big nough or educated enoguh to argue or complain and were small enough to fit between tight fitting machinery that adults couldn't get between
Detail 3:There was no restriction on the age of workers, nor on the number of hours that they could work. This led to children as young as 8 or 9 being required to work 12 or more hours a day.
VI. CONCLUSION:
There were several changes before and after the Industrial revolution. The changes were positive and negative. Some areas did not change.

Before (not yet a thesis statement):

If you do not know the impact of the Industrial revolution, you will not understand anything in this essay. This topic is very good to study because you know about the different views. The Industrial Revolution changed Britain and if it did not happen Britain would not have great technological advances of the 20th century.

After (thesis statement):
The Industrial Revolution changed Britain for the better and led directly to great technological advances of the 20th and 21st centuries.

The rest of what you wrote and called a thesis statement needs to be deleted. Then ... write an introduction in such a way that your thesis statement (notice it's singular, ONE sentence) is the last sentence in the introductory paragraph.
http://leo.stcloudstate.edu/acadwrite/intro.html

Note: Do not use "I" or "you" or any of these pronouns' forms in your paper -- anywhere!

To improve the readability of your sentences, you may want to consider breaking them down into shorter, more concise statements. Here's an edited version of your text:

Thesis: To fully grasp the significance of the Industrial Revolution, it is essential to understand its impact. This topic is worth studying because it offers insights into different perspectives. The Industrial Revolution transformed Britain, leading to remarkable technological advancements in the 20th century.

II. BODY PARAGRAPH 1:
Opening Sentence: The Industrial Revolution, which occurred from the 18th to the 19th century, brought about significant changes.

Detail: It affected agriculture, manufacturing, mining, and transportation, profoundly influencing the social, economic, and cultural conditions in the United Kingdom.

Transition/Opening Sentence: Before the Industrial Revolution, Britain was a vastly different place.

Detail 1: Communication with people from other parts of the country was challenging. News relied on messengers or travelers.

Detail 2: Mobility was limited, with no cars, buses, or airplanes.

Detail 3: Food and clothing were primarily produced locally, with agriculture providing for only a few towns.

V. BODY PARAGRAPH IV:
Transition/Opening Sentence: While the Industrial Revolution instigated widespread changes, not every area experienced the same level of transformation.

Detail 1: The growing number of factories required a large workforce, and employers sought to avoid high wages.

Detail 2: Children emerged as ideal employees due to their cheap labor, lack of education, and small size for maneuvering machinery.

Detail 3: No restrictions existed on workers' age or working hours, resulting in children as young as 8 or 9 being required to work long shifts of 12 hours or more.

VI. CONCLUSION:
The Industrial Revolution brought forth numerous changes, both positive and negative, across various aspects of society. However, certain areas remained untouched by these developments.