What do you mean my blood’s not blue??

First of all, what’s a misconception?

According to Merium-Webster: a wrong or inaccurate idea or conception

What happens if a student comes up to you and asks:

  • Why do girls have one more rib than boys?”
  • Are all cells as pretty as the ones in the book?”
  • Will an apple grow in my stomach if I eat a seed?”
  • How is global warming real if it’s snowing right now?”

How are you going to respond? What if they don’t believe you?

Well, you’ve come to the right place! Here’s an example of how to deal with a common misconception students may have.

Misconception: Blood is blue in your veins, but turns red when it hits Oxygen.

blue blood red blood

First of all, it’s important to understand where these misconceptions stem from.

Here is a common diagram of a heart:

See the blue? This could be one of the ways the blue blood misconception comes about.

Here’s what’s probably the most common way this misconception comes about:

Look down at your wrist. See the blue veins? Without any background information, it can be easy to see why someone would think blood is blue when in the vein.

Okay, so now that we know why students may think that their blood is blue, here are some ways to combat this misconception (or any misconception in general).

Option #1: Find a video that may help explain the misconception.

Option #2: Get rid of anything in your classroom that may be encouraging the misconception.


  • Having the heart diagram on the left would be encouraging the misconception that blood is blue. Having the heart diagram on the right would be combatting the misconception and giving students the right idea of what color blood actually is.

Option #3: Have examples on hand that combat the misconception.

  • Talk about a blood donor clinic. When blood is getting donated, it is red. This blood is not oxygenated since it doesn’t contact oxygen during it’s trip into the bag.

Here’s a great video of actual teachers discussing how to address misconceptions:

These teachers are:

  • Activating student’s prior knowledge
  • Uses these misconceptions to their advantage by making their instruction more effective


  1. Katie! I love that you found concrete ways to help a student reassess their beliefs. So many of us held the “blood is blue” misconception for so long that it can be hard to let go of the idea. I wouldn’t have thought about misinformation in the classroom itself. I imagine a lot of misconceptions that were formed or confirmed based on confusing models! Great post!

    • Peter, thank you so much for the feedback! I agree that misconceptions can be hard to let go of purely because they have been held onto for so long.

  2. Hello Katie!
    Excellent post! I have to admit that I used to think my blood was blue as a child, lol. After watching your video, I understand why it isn’t. I like your ways to combat this problem. I also like your example of blood being blue! A lot of people actually still think that. It is a common misconception and with the use of reasoning, proble-solving, and open-mindedness, you can know down this misconception. I would add that as a teacher, you must be open-minded to cultural and religious beliefs. You must accept everyone’s beliefs and not negate them. I learned this as a teacher. You must be open-minded to new ideas to allow your students to be open-minded as well. When I was student teaching, I saw many different kids from different cultural and religious backgrounds. I met a Muslim kid, African American kids, and Latino kids. All of them have aweome cultures and beliefs and we must be open-minded to them. This does not necessarily mean that we agree. How do you think we can accomodate different cultures and beliefs in the classroom? I like how you talk about the ways that you would knock down the misconception. Removing things that are unhelpful to the misconception are key. You showed the diagram of the heart. I agree that one of them should probably be removed if we are to know down misconceptions. Some people would say that science is always changing, and I agree, but we must teach the children what we know as fact, as of now, and update the information later. What do you think? I love your videos as well. I will end with telling you about my own biology misconception. I have a chocolate lab, named Moses. I used to think that his chocolate color was because of a genetic mechanism called codominance, where a mixture of white and black genes made the chocolate color. Later, I learned that it is not that. It is a process called epistasis where one gene controls the expression of another. If I did not have that misconception and rebuild based upon the misconception, I wouldn’t of come to the correct answer. I am smiling as I right this. Moses the chocolate lab is awesome! Great post and I love how you tie it all together, I also gave various examples of common misconceptions in biology. There are many!

    Delaina 🙂

    • Thank you for the feedback! As for making accommodations for different cultures and beliefs in the classroom, I think that sometimes it’s best to not bring them up if you don’t need to. This can be a touchy subject for students and if beliefs don’t need brought up, then I don’t see the point in bringing them up in the first place. As for individual students, it could mean a lot to them if you, as a teacher, show interest in their ethnic background. This could show the student that you are genuinely interested in their lives and how they live their lives.
      When you bring up the point of teaching what we know as fact as of now, I think that we can only teach what we know. But I also believe that it’s important to be transparent with students. Meaning that it’s important to let them know that science is always subject to change, and that not everything they are learning now will be the same in years to come.
      Thanks again for the feedback!

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