(CNN) -- Robert Zimmerman Jr., the brother of the man who shot and killed 17-year-old Trayvon Martin, apologized for his controversial and offensive tweets.

In one, Zimmerman juxtaposed a photograph of Martin with one of 17-year-old De'Marquise Elkins, one of two teenagers charged with killing a baby in Georgia.

Both Elkins and Martin appear to be flipping off the camera.

"A picture speaks a thousand words. Any questions?" the tweet reads.

In another tweet, Zimmerman writes: "Lib media shld ask if what these2 black teens did 2 a woman&baby is the reason ppl think blacks mightB risky."

Speaking on CNN's Piers Morgan Live on Wednesday night, he apologized for the messages, saying they weren't the "right thing to do."

"I realize those were controversial and offensive and I did publicly apologize for them," he said. "I'm a human being. I'm being upfront about what I did. I made a mistake ... Unfortunately (it) may not have helped George."

5 things to know about the case

His brother, George Zimmerman, has been charged with second-degree murder. Zimmerman acknowledged shooting Martin but said it was in self-defense. Attorneys for Martin's family have accused Zimmerman of racially profiling Martin and shooting him "in cold blood."

Robert Zimmerman Jr. said he was trying to make a larger point in his tweets about the "media and their honesty in portraying the person who encountered my brother February 26, 2012.

Letters to Zimmerman show split opinions

"We've been led to believe that it's a junior-high-school-aged person because of the pictures," he said, referring to Martin. What are the answers to this following set of questions: 1. How old was Trayvon Martin?
2. What happened to him?
3. Did he survive?
4. Who apologized for his tweets?
5. Who is he related to?
6. What are Elkins and Martin doing?
7. What is the charge in the case?
8. What shoe did the tweeter appear on?
9. What is George Zimmerman charged with?
10. Did he admit he had done it?
11. Did he say it was self defense?
12. When did the shooting occur?
Answer: 1. 17.
2. He was shot.
3. No.
4. Robert Zimmerman Jr.
5. George Zimmerman.
6. Flipping off the camera.
7. Killing a baby.
8. Piers Morgan Live.
9. Second-degree murder.
10. Yes.
11. Yes.
12. 2012.

One day Tom was playing with his younger brother Paul beside the well near their home. Suddenly Tom fell down the well. Paul was frightened. Their parents were not at home. Their father was working in the factory and their mother was helping a neighbor. Tom called his younger brother, Paul. Paul looked at the bottom of the well and saw his brother standing in the water of the well. Tom was five feet tall and the water was only three feet deep. Paul was glad to see his brother safe in the well. Then he ran home and brought a long rope. He was only six and not very strong, so he could not pull Tom out. He was thinking hard and finally had a good idea. He tied one end of the rope to a tree and threw the other end to his brother in the well. Then Tom climbed up the rope and got out of the well. He thanked his brother first and went home to exchange his wet clothes. What are the answers to this following set of questions: 1. Who was Tom playing with?
2. Where were they playing?
3. Where was the well?
4. What happened to Tom?
5. How did Paul feel about it?
6. Where was Tom's Dad?
7. Were Tom and Paul related?
8. How so?
9. Was Tom drowning?
10. What did Paul do?
11. why?
12. What did he do with one end of the rope?
13. And the other end?
14. How old was Paul?
15. How deep was the water?
16. How tall was Tom?
17. Did Tom get out?
18. What was the first thing he did?
19. Then what?
20. to do what?
Answer: 1. Paul
2. beside the well
3. near their home
4. fell down the well
5. frightened
6. working in the factory
7. yes
8. brothers
9. no
10. ran home
11. brought a long rope
12. tied it to a tree
13. threw to his brother
14. six
15. three feet
16. five feet tall
17. yes
18. thanked his brother
19. went home
20. exchange his wet clothes

Children can spend hours a day looking at computer screens and other digital devices . Some eye doctors say this leads to an increase in "computer vision syndrome ." Nathan Bonilla-Warford is an optometrist in Tampa, Florida. He has seen an increase in problems in children. "A lot more children come into the office either because their parents have noticed that they have headaches or red or watery eyes or discomfort, or because their nearsightedness appears to be increasing and they're worried," he says. Dr. Bonilla-Warford says part of the problem is that children may be more likely to pay no attention to early warning signs than adults. "Even if their eyes start to feel uncomfortable or they start to get a headache, they're less likely to tell their parents, because they don't want to have the game or the computer or whatever taken away," he explains. He says another part of the problem is that people blink less often when they use digital devices. He says, "A person who uses an electronic device blinks about one third as much as we normally do in everyday life. And so that can result in the front part of the eye drying and not staying protected like normal." Eye doctors offer suggestions like following which is known as the 20/20/20 rule. That means every twenty minutes look away twenty feet or more for at least twenty seconds from whatever device you're using. Other suggestions include putting more distance between you and the device and using good lighting. Of course, another way is to spend less time looking at screens. Many experts say children should spend no more than two hours a day using digital devices--with no screen time for children under two. But not all eye doctors have noticed an increase in problems in children. Dr. David Hunter, from Children's Hospital Boston, has not seen an increase in his practice. "While it is possible to develop _ looking at screens for a long period of time, there's certainly no proof that it actually causes any damage to the eyes." he says. What are the answers to this following set of questions: 1. Who is in Tampa?
2. Is he a dentist there?
Answer:
1. Nathan Bonilla-Warford
2. yes