Mystery Powders

Container of flour (Karolina Grabowska, Pixabay)

Container of flour (Karolina Grabowska, Pixabay)
How does this align with my curriculum?
Students investigate the properties of a variety of everyday solids (powders) and liquids to determine the identity of an unknown solid (mystery powder).
Overview
Activities | Timing | Student grouping | Description |
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Minds-On: Mystery Powder Fair Test | 15 minutes | Large group | Teacher introduces the mystery powder and demonstrates how to do a fair test (controlled experiment). |
Action: Exploring Powders | 40-50 minutes | Small group | Students use a fair test on a variety of white powders to determine which one is the mystery powder. |
Consolidation: Polling Results | 20-30 minutes | Independent and large group | Students determine if the observed changes were physical or chemical and learn the identity of the mystery powder. |
This lesson can be done over a few days.
Materials and Preparation
Teaching and Learning Activities
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Minds-On: Mystery Powder Fair Test 15 min.
Instructions | Teaching Tips |
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Show students the jar filled with the mystery powder (baking soda or powder). Tell them that you are unsure of what this powder is and you need their help to figure it out. Ask students to suggest ways to determine what kind of powder it is. Students may make suggestions such as feel it, taste it, smell it, or look at it up close. Pass the jar around so that students can take a closer look at the powder. Remind students that when they are using their senses to gain information, they are using the skill of observation. Have students make observations of the powder and record them on the board or a sheet of paper under the headline “Observations”. Ask students to predict what they think will happen if vinegar is added to the powder. Make notes of students' predictions on the board or a sheet of paper under the headline “Predictions”. |
LanguageConsider creating a word wall of terminology that students will encounter over the course of this lesson such as powder, grainy, coarse, smooth, matte, shiny, rough, bubbles, gas, independent variable, controlled variable, dependent variable, etc. SafetyRemind students to never put anything in their mouths, to smell, or to touch, unless told it is safe to do so by a trusted adult. In science we do not use our senses of taste, touch or smell to make observations unless we know it is safe to do so. IdeaIf it is conducive to your classroom you could have students use their sense of taste if they wish, provided there are no allergies to any of the powders. All of these suggested powders from the materials are safe for ingesting. |
Explain or review the concept of a fair test (also known as a controlled experiment) with students. In a fair test, only one thing (the independent variable) is changed at a time. Everything else (the controlled variables) are kept the same. That way, only the independent variable leads to the results (dependent variable). Explain that in the test you are doing, and in the testing they will do, only the powder will be changed. The volume of liquids and solids, the type of liquid, the length of time stirring, will remain the same for each. Carefully measure out 1 tsp of the mystery powder into a small cup or dish. Then measure and add 1 tsp of vinegar to the powder. Have students closely observe as you mix the two together. Ask students to describe what they have observed and write these new observations on the board or a sheet of paper under the heading “Results” Now tell students that they will be conducting their own fair test with the powders. Explain to students they are matching up the physical properties and chemical reaction of the known powders to the "mystery" one. It is up to them to see if they can discover which of their powders is the mystery powder in the jar. |
Action: Exploring Powders 40-50 min.
Instructions | Teaching Tips |
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Arrange students in groups of 4-5. Provide each group with 1 bag of each of the labeled white powders and with the Mystery Powder Predict and Observe Chart reproducible [Google doc] [Word doc] [PDF]. ![]() Note: Modify the chart to reflect the powders that the class will be testing. Have the students delegate the tasks in their group (e.g., one person is the note taker, another person can measure out the vinegar, another can add the vinegar to the powder, etc.). Students can take turns doing these tasks. Explain the instructions to students. You could do this by providing each group with the Mystery Powder Fair Test Task Card reproducible [Google doc] [Word doc] [PDF] or projecting the page digitally on a screen. ![]() Review each of the steps with students to ensure that they understand each step. Note: Below are some examples of powders mixed with vinegar for your reference. ![]() Image - Text VersionShown are four colour photographs of four cups with white powder and liquid mixed together. Observe students’ interactions with the materials and the fair testing process, and document observations, including discussions and questions raised, to determine the direction of future learning. Facilitate discussion with students about their findings and how the information gathered can be used to determine what is in the “mystery powder.” |
Nature of ScienceScientists do not work alone. They work on teams where different members bring different skills and abilities to the task they are working on. LanguageReview what a prediction is to ensure students understand the concept before beginning the activity. Suggested prompts can include:
SafetyRemind students to never put anything in their mouths unless told it is safe to do so by a trusted adult. Images and VideosAdapt the Mystery Powder Predict and Observe Chart reproducible to include the powders that the students will be using. Nature of ScienceStudents use the Computational Thinking Skills of pattern recognition and logical thinking as they work to determine how each powder is like or unlike the mystery powder. |
Consolidation: Polling Results 10 min.
Instructions | Teaching Tips |
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Conduct a poll to have students vote on which powder they think is the mystery powder. You could do this by a show of hands, using a digital program (e.g., Poll Everywhere, Plickers, etc.) or on chart paper. At the end look at what the most common prediction was and ask the class if they agree. Ask students to explain their reasoning. Reveal to them what the mystery powder was (baking soda or baking powder). |
IdeaFor a no tech option, have the powder names written on the board and give students a sticky note, chalk or marker and leave a mark under the powder they want to vote for. Nature of ScienceThis sharing of results and conclusions is analogous to what scientists do. Sometimes results are shared with small groups, at conferences, etc. Feedback could send them back to the lab to do more research or might help them clarify their thinking. The final step is usually that results are published in a magazine for more scientists to learn from the work they did.
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The final task will draw on students' prior knowledge of physical and chemical changes. If students are familiar with the topic, go on to the last step of these instructions. If students are not familiar with the topic of physical and chemical changes you could activate their prior knowledge by asking discussion questions and recording student answers or showing them the Physical and Chemical Changes interactive presentation [html] [Google slides] [pptx] [PDF]. In addition, seeding some photo examples might be helpful for students. ![]() Image - Text VersionShown are five colour photographs of chemical reactions, arranged and labelled on a blue background. Have conversations with students about the differences between physical and chemical changes. |
DiscussionsDiscussion prompts can include:
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After students have reviewed information relating to physical and chemical changes, you could have them complete the Physical or Chemical Change Identification Chart reproducible [Google doc] [Word doc] [PDF] either individually, in small groups, or as a class. ![]() Note: Modify the chart to reflect the powders that the class will be testing. Students could hand in the completed reproducible which could be used as an assessment of learning. For reference:
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IdeaThe Physical or Chemical Change Identification chart could be completed by asking students to raise their hands for each powder. |
Background Information for Teachers
Mystery Powders

Image - Text Version
Shown is a colour photograph of a hand holding a container filled with white powder, and pouring white liquid into it.
A hand extends from the bottom edge of the image. It holds the handle of a grey container, half full of fine, white powder and a small whisk. A white bottle comes in from the top of the image. Thick white liquid is being squeezed from it into the powder. In the background is a large, stainless steel sink.

Image - Text Version
Shown is a colour photograph of glass jars filled with different cream and beige powders.
The camera looks down on a white table. Five clear glass jars are open, showing their contents. Each powder has a similar consistency, but a slightly different colour. These are shades of beige and cream.