Revise the mixed sentences so that the beginning of each sentence fits logically with its end. If sentence is correct cirle it.

1. By showing babies plain, black-and-white images will help them learn to recognize shapes and focus their vision.

Showing babies plain, black-and0white images helps them learn to recognize shapes and focus their vision.

2. Babies can see their parents’ faces but will not respond with a smile until they are a few weeks old.

Babies can see their parents' faces but cannot respond until they are a few weeks old.

3. Babies may gaze intently into a small, unbreakable mirror attached to the inside of their cribs.

Correct

4. While following an object with her eyes is when eye coordination develops.

Following an object with her eyes is where eye coordination develops.

5. Because of a newborn’s limited ability to see color forces him to focus only on bright colors.

Because newborn's limited ability to see color they he only focuses on bright colors.

6. The reasons babies occasionally cross their eyes is because they are perfecting their tracking skills.

Correct

7. Whether a light sleeper or a heavy sleeper, a typical baby does not need complete silence in order to rest well.

Light sleeper or heavy sleeper, a typical baby does not need complete silence in order to rest well.

8. The fact that newborns can vary dramatically in their sensitivity to sounds and ability to sleep in noisy environments.

Correct

9. The reason that a two-month-old baby turns her head toward her parents’ voice is because she is beginning to recognize familiar sounds.

The reason a two-month-old baby turns her head toward her parents' voice because she begins to recognize their sounds.

10. Through changing his facial expression indicates he may find a particular sound soothing or comforting.

Correct

http://www.jiskha.com/display.cgi?id=1293727557

Why did you change the second sentence? It was grammatically correct and you replaced it with something else that has a different meaning. Perhaps you were bothered by the change from present tense to future in two clauses of the same sentence, but that is OK in this case. A response (a smile) happens slightly in the future, relative to the present (seeing a person)

I agree with DrWLS that #2 was correct in the original.

So are #s 3 and 7.

Your correction for #1 is good.

Rethink these:
#s 4, 5, 6, 8, 9, and 10.
Read my comments in the link I gave you above.

1. By showing babies plain, black-and-white images, it helps them learn to recognize shapes and focus their vision.

Explanation: To revise the sentence and make it more logically coherent, we can rearrange the sentence so that "By showing babies plain, black-and-white images" is followed by the action or result it causes, which is "it helps them learn to recognize shapes and focus their vision."

2. Babies can see their parents' faces, but they will not respond with a smile until they are a few weeks old.

Explanation: The original sentence is already correct. No revisions needed.

3. Correct

Explanation: The sentence is already logically coherent. No revisions needed.

4. Following an object with her eyes is where eye coordination develops.

Explanation: To revise the sentence, we can rearrange it so that the cause (Following an object with her eyes) is followed by the result or development it leads to, which is "eye coordination develops." By doing this, the sentence becomes more logically consistent.

5. Because of a newborn's limited ability to see color, they only focus on bright colors.

Explanation: To revise the sentence, we need to connect the cause ("Because of a newborn's limited ability to see color") with the result or consequence it leads to, which is that "they only focus on bright colors."

6. Correct

Explanation: The sentence is already logically coherent. No revisions needed.

7. Light sleeper or heavy sleeper, a typical baby does not need complete silence in order to rest well.

Explanation: The original sentence is already correct. No revisions needed.

8. Correct

Explanation: The sentence is already logically coherent. No revisions needed.

9. The reason a two-month-old baby turns her head toward her parents' voice is that she begins to recognize their sounds.

Explanation: To revise the sentence, we can connect the reason ("The reason a two-month-old baby turns her head toward her parents' voice") with the result or consequence it leads to, which is that "she begins to recognize their sounds."

10. Correct

Explanation: The sentence is already logically coherent. No revisions needed.