Top image: Flour (photo by Karolina Grabowska via Pixabay)

Setting the Stage

Students use their senses to observe, explore and interact with materials in the world around them. Their natural curiosity leads them to mix materials together - just to see what will happen. This inquiry builds on this natural tendency. It provides opportunities for students to compare properties of familiar solids and liquids using their prior knowledge and experiences with them. Students then predict what will happen when the solids and liquids are mixed together, and connect their prior knowledge with their observations to solve the problem of the ‘mystery powder’.

Mystery Object (Tim Green via Wikimedia Commons)

This inquiry could begin from:

  • sharing a mystery object. Discuss using questions such as:
    • “How can we get some clues about what this object is or what it might
      be used for?”
      (This may include ideas like asking questions about it,
      using our senses to get hints, using prior knowledge, etc.)
    • “Where do you predict an object like this might be used? Why do you think that?”

  • Front cover of The Boxcar Children: The Pizza Mystery by Gertrude Chandler Warner
    (cover image via Open Library)

  • a book such as The Boxcar Children: The Pizza Mystery. Discuss using questions such as:
    • “What is a mystery?”
    • “What skills would be helpful to have when you are solving a mystery?”
    • “As we read the story, watch for places where the children in the story used the skills we discussed. What other skills did they use to solve the mystery that were not discussed?”



Materials and Preparation (Click to Expand)


  • a variety of white ‘powders’ such as flour, icing sugar, salt, cornstarch, baking powder, baking soda, baby powder, powdered milk, Plaster of Paris, chalk dust, etc.
  • resealable bags (one for each powder)
  • eyedroppers (or 1 ml medicine measuring cups/syringes)
  • hand lenses/magnifying glasses
  • paper or plastic plates
  • Powder Observation Chart
  • small plastic or paper cups or shallow dishes
  • standard measuring spoons - i.e., 5 ml (1 teaspoon) for the powders and 1ml (1/4 teaspoon) for the liquids
  • stir sticks (plastic or wood)
  • water
  • white vinegar


  • Fill small snack-sized resealable bags with samples of each powder (one bag of powder per group for each powder you are using); label the bags.
  • Optional: for initial observations of the dry powders, draw (or cut out) a circle for each powder you are using on paper/plastic plates; label circles with the names of the powders.
  • Prepare the ‘mystery powder’ using two to three of the powders. Fill small snack-sized re-sealable bags of the mystery powder for testing (one per group); label the bags.

What To Do

Students use the Making Comparisons learning strategy and the skills of Observing, Predicting and Making Connections as they investigate the properties of a variety of everyday solids (powders) and liquids to determine the composition of an unknown solid (mystery powder).


  • observe the powders with and without the use of a hand lens, and compare the powders using words such as fine/coarse, compact/loose, matte/shiny, rough/soft, etc.
  • record their observations on a chart (see sample in Materials section)
    • Educator reminds students to never put anything in their mouths unless told it is safe to do so by a trusted adult.
  • predict what will happen when water is added to each of the powders
    • Educator models the concept of a fair test by carefully measuring out 5 ml of one of the powders into a small cup or dish, using an eyedropper to add 1 ml of one of the liquids to the powder, then stirring the liquid and powder together.
  • observe the mixture created by the educator, checking their observations with their predictions.
  • record their observations on the chart and compare their observations of the dry powder to those made after the liquid was added.
  • predict what will happen to each of the other powders when the liquids are added and record their predictions in the appropriate place on the chart.
  • work in small groups to repeat the fair test with the other liquids and powders, recording their observations on the chart.
    • Educator stresses the importance of fair testing - using the same amount of each of the powders and liquids.
    • Educator observes students’ interactions with the materials and the fair testing process, and documents observations, including discussions and questions raised, to determine the direction of future learning.
    • Educator facilitates discussion with students about their findings and how the information gathered can be used to determine what is in the “mystery powder.”
  • repeat the test on the “mystery powder” and record their observations on the chart.
  • use their observations to draw conclusions about the contents of the mystery powder, justifying their conclusions with examples from their observations.


Observe and document, using anecdotal comments, photos and/or video recordings, student’s ability to:

  • Observe - students make use of all of their senses (except taste unless directed to do so by the educator) to collect information about the powders
  • Predict - students make predictions about how liquids will affect each of the powders
  • Make Connections - students draw conclusions about which powders make up the mystery powder and justify their conclusions based on information gathered

Co-constructing Learning

Saying, Doing, Representing

Educator Interactions:
Responding, Challenging

Students observe and compare the powders with and without the use of a hand lens.

  • “What are some words that you used to describe each of the powders?”
  • How did your description of the powder change after you looked at it through the hand lens?”
  • “Which of the powders do you think you have seen before? Where did you see it? How and why was it being used when you saw it?”

Students record their observations for future reference.

  • “Why is keeping an accurate record of your observations important?”
  • How will these observations help you to identify what is in the mystery powder?”

Students predict what will happen when each of the powders, including the mystery powder, is mixed with each of the liquids.

  • “What does this liquid remind you of? How can that help you make better predictions?”
  • “How can you use your prior knowledge of this powder to make better predictions about what will happen when it is mixed with the liquids?”

Students check their predictions, following the procedures for a fair test.

  • “How did each liquid respond when added to different powders? What words could you use to describe what you observed? How did you record these observations so that you can use them later? How will those observations help you to determine what powders are in the mystery powder?”
  • “I notice that you are using the same number of drops of liquid with the mystery powder as you did with the others. Why is that important to do?”

Students draw conclusions about what powders the mystery powder contains and justify their thinking with observations from the data they collected.

  • “Your group concluded that the mystery powder contains baking soda and corn starch. What observations led you to that conclusion?”
  • “How did your descriptions of the effects of adding liquid to each of the powders help you to predict which powders were in the mystery powder?”
  • “Would the use of your sense of taste have helped you in determining what was in the mystery powder? Why/why not?”

Cross-Curricular Connections


  • communicate orally in a clear, coherent manner, presenting information in a readily understandable form (e.g., present conclusions about the mystery powder including details of how the conclusion was made)
  • use specialized vocabulary (e.g., “The sugar dissolved in both of the liquids.” “We saw no change in the salt when we added the vinegar.” “The water made the baking soda feel sticky.”)

Mathematical Thinking

  • estimate, measure and record capacity (e.g., use standard measures when mixing liquids and powders)
  • learn through problem-solving (e.g., solving the problem of the mystery powder provides opportunities to learn about properties of familiar solids and liquids and how they interact as well as how to conduct a fair test)
  • reason and prove (e.g., that one liquid will not always produce the same result when mixed with different powders)
  • represent thinking and learning (e.g., using pictures, diagrams, graphs, tables, numbers, words, and/or symbols to show how they determined the components of the mystery powder)

Extending the Learning

If your students are interested in learning more, the following may provoke their curiosity:

  • Students may wish to repeat the inquiry with the following variations:
    • using different liquids and/or different powders
    • increasing the amount of powder but keeping the amount of liquid the same
    • decreasing the amount of powder but keeping the amount of liquid the same
    • increasing the amount of liquid but keeping the amount of powder the same
    • decreasing the amount of liquid but keeping the amount of powder the same

Students make predictions about what will happen, whether the effects will be the same or different from what was observed in previous investigations, then check their predictions to see how accurate they are and if they see a pattern emerging (e.g., does one liquid produce the same results when added to a variety of different powders? does one powder always react the same way regardless of the liquid added to it?).

Cinnamon Sugar, Sugar, and Cinnamon
Sugar (photo by ulleo via Pixabay)