Combining dish soap and milk

The milk constituents:

The soap molecule constitute:

What happens when we combine dish soap and milk?

2 People tried to answer this question

The milk contains fats and peoteins in the solution, in addition to other components. The dish soap drop reinforces the bonds (because it is all hydrophilic) between the proteins or the fats with the solution and the food color moves to the side of the plate.

The milk contains fats and proteins in the solution, in addition to other components. The dish soap drop breaks the bonds between the proteins or the fats from the solution, and they are chasing after the other free fat molecules so they will create bonds together.

The milk contains nothing but water and a white color. The dish soap drop breaks the bonds between the white color and the solution, and the food color reacts with the white color.

The milk contains fats and peoteins in the solution, in addition to other components. The dish soap drop reinforces the bonds (because it is all hydrophobic) between the proteins or the fats with the solution and the food color moves to the side of the plate.

1.  Pelekhov Veronika (2014-12-20 15:00:00)

Alina, hello,

Very good idea for a question, the video is colorful and brings attention to the phenomenon. Household materials and clear, well built video allow repeating the experiment at home. The picture with a soap molecule explains in a simple way the structure of the molecule, which is important for the phenomenon understanding.

The table a little bit complicated because of the High SCC Milk information, it can affect concentrating on the necessary information.  

I am not so sure about the statement in the right answer which is saying that "fat molecules are free to react with the food color".

 I tried to find some information about the phenomenon, here is a link to some scientific explanation from one of the Canadian universities:

 The point on the map helps to understand what happens in the video and related well to the topic.  Maybe you should add one or two sentences about the way the structure breaks the bonds and which bonds are in fats and proteins.


Small misprint - in the right answer you've written "peoteins" instead of "proteins".

Hope I managed to help you a little bit.

You made a good work!

Good luck,



2.  Mashaal Alona (2017-12-20 15:00:00)
Feedback by Aona

Hi Alina,

The experiment you present in your question is very beautiful! The movie you created will probably be very attractive for students, and will arouse curiosity. The question requires high cognitive level in order to answer it.

Here is my feedback:

·        I looked at the curriculum of grades 7,8 and 9, and didn’t find a subject which clearly provides the knowledge and ability to answer your question. Did you make sure that the required knowledge for this question is indeed taught in class?  

·        I didn’t find English mistakes in your text, but some sentences are not totally clear and might create confusion. For example: “dish soap drop reinforces the bonds between the proteins or the fats with the solution”. The word ‘with’ doesn’t quite fit here (and the word ‘from’ in a similar sentence at your correct answer), and the ‘or’ is confusing. A separation like “the bonds between the protein and the solution, or the bonds between the fat and the solution” might help.

·        The correct answer is not totally correct. The movement is due to the reaction between the soap, fat and water. This movement will also happen without the presence of colors, but the colors enable us to see this movement. I’m sure you know this, but the correct answer does not clearly say this.
By the way, this phenomenon is also related to surface area tension, and the described reaction with the soap is not the only reason for the movement we see. Maybe it should be noted somewhere that this is part of the explanation to the phenomenon.

·        It is not correct to describe milk as a solution which contains fats, protein, and others. It is not a solution, but a colloid (emulsion).

·        According to the assignment instructions the question should include a simulation or animation. You included a movie you created which might be accepted instead. Anyway, I tried to look for a relevant simulation at the Phet website, but couldn’t find one. I found two movies with nice animations, that explain in a simple and visual way how soap works:

·        The information point you added on the map has indeed a connection to the question, but it should provide additional information that can help the student answer the question, and it should include an original movie, related to this extra information, and connects the question to the student’s everyday life. Your information point doesn’t include all that. My suggestion is to add information about how soap works. This information will help the student answer your question.  The movie should deal with the same subject. We’ve been asked to create an original movie here, but since you created an original movie for the question itself, it might be ok to use a non-original movie – ask the course stuff. In such case, the movies I mentioned earlier might feet here.
Notice that you can’t use the movie you already created as the movie for the information point, since it doesn’t include extra information, it is part of the question itself.

·        On my opinion, the distractors you wrote are a bit problematic: There are two answers which contain the word hydrophilic/hydrophobic, both are wrong answers. In the information point these words are used. The correct explanation is indeed related to hydrophilic/hydrophobic properties, but the correct answer doesn’t mention them. This might be an unnecessary deception for the student. I think all answers should include this words.  

I added a point on the map which provides some information about milk, and as such, it can help understand better what happens in the experiment you presented.

Good luck!


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