Question

What is a good transition sentence and thesis statement about Sundials?

Answer 1

Well, we cannot give you the answer.

But, a thesis statement is basically your opinion + the topic
A thesis is rather specific than vague or generalized sentence about a specific item (like a research paper or a story).

Example of a weak Thesis Statement: The people of Mesopotamia learned how to control the Tigris River and invented the wheel.

It is a weak Thesis Statement because you do not know whether the story/article is about inventing the wheel or the people controlling the Tigris River.

Answer 2

Example of a strong Thesis Statement: The development of the wheel in Mesopotamia changed human civilization more than any other invention.