Discrepant Event

Discrepant events are a perfect way to get the students attention at the beginning of a lesson. Discrepant events help student learn the material because they should be interest sparkers and create questions that the student is interested in finding the answer to through out the lesson. this lesson is great because it shows students how a chemical reaction occurs.


Discrepant Event Demonstration

What’s a Chemical Reaction?

Teacher Handout


Materials list:



Baking soda

Empty water bottle




Directions with safety considerations:

  1. Blow the balloon up a little bit to stretch it out.
  2. Put protective eye wear one.
  3. Make one balloon with two teaspoons of baking soda in it using the funnel.
  4. Now get the empty water bottle and fill it half way up with vinegar.
  5. Put the balloon over the bottle, but do not let any baking soda get in the bottle yet.
  6. Ask the students what they think will happen when the baking soda goes into the plastic bottle. Also ask why?
  7. Now take the baking soda and pour it into the bottle. Watch the results.
  8. Ask the students why they think this reaction occurred.
  9. Now tell the students why it occurred.

-The reaction that we just saw was a chemical reaction. When you mix baking soda that contains sodium bicarbonate which is a base when mixed with vinegar which is an acetic acid they react with each other. The gas that is created when this happens is carbon dioxide (CO2) which is why we saw all the little bubbles forming in the bottle. The balloon fills up because as the chemical reaction occurs the gas needs to escape from the bottle. Since we have the balloon wrapped around the top the air fills into the balloon; blowing it up! We create CO2 when we breath as well.


Description of the use in an elementary classroom:

This activity can be used in a fifth-grade classroom to discuss mixtures and solutions. Students are given a hands on opportunity to mix two elements and visibly see the outcome. I also think that is interesting to them that we create Co2 when we breath as does this experiment.

5.4 The student will investigate and understand that matter is anything that has mass and takes up space; and occurs as a solid, liquid, or gas. Key concepts include

  1. e)  mixtures including solutions.


Resource Citation:





Student Hand out:


What’s a Chemical Reaction?


Answer the following questions and draw pictures when necessary:

 Make a prediction on what you think will happen when we combined baking soda with vinegar:

 Why do you think this will happen?

 Draw a picture of the result after the experiment is complete:


The reaction that we just saw was a chemical reaction.  This reaction is caused when you mix baking soda which has sodium bicarbonate with vinegar which is acetic acidic you get the bubbling reaction of CO2 being created as the solution  Does carbon dioxide sound familiar? Well it is what we as human’s breath out every day. As with our lungs we cannot just keep the carbon dioxide in ourselves. So, we breath it out just as with the bottle with the mixture had to release its CO2 and filled up the balloon.


Leave a Reply

Your email address will not be published. Required fields are marked *