Mystery Powder Detectives

Overview

Students investigate four mystery powders by observing physical properties, testing solubility in water, recording results, and using evidence to make predictions. The lesson builds on students’ prior experience making careful observations and introduces the idea that scientific explanations must be supported by evidence.

Learning intentions

• I can make careful observations using scientific vocabulary.
• I can follow a multistep testing procedure safely and accurately.
• I can record information in a table or drawing.
• I can use evidence to predict the identity of an unknown substance.
• I can explain how an observation supports my prediction.

Success criteria

• I can describe each powder’s color and appearance without guessing its identity.
• I can follow the LOOK–TEST–RECORD–PREDICT steps in order.
• I can record whether each powder dissolves, does not dissolve, or is uncertain.
• I can make a prediction using the sentence: “I think Powder ___ is ___ because I observed ___.”

Curriculum links

• Citing specific textual evidence to support analysis of science and technical texts.
• Following precisely a multistep procedure during an experiment or technical task.
• Analyzing an author’s purpose when explaining a procedure or experiment.
• Integrating information in words with information shown in a table or visual record.

Lesson structure (40 minutes)

1. 0–4 min · Hook and purpose. Teacher displays the mystery challenge on the introduction and mystery-powder slides, explains that scientists identify materials using evidence, and reminds students never to taste or directly smell an unknown powder. Students silently predict whether looking alone will be enough to identify every powder, then share with a partner.

2. 4–8 min · Model the procedure. Teacher models examining one sample with a magnifying glass, describing only observable features, and completing one example on the mystery-powder recording sheet. Teacher explicitly demonstrates the sequence LOOK, TEST, RECORD, PREDICT using the procedure slides. Students identify the difference between an observation (“white and grainy”) and a guess (“it is sugar”) and repeat the safety expectations.

3. 8–22 min · Observe and test. Teacher places students in nine pairs and gives each pair four labeled cups, magnifying glasses, craft sticks or plastic spoons, and four small cups of water. Teacher directs students to complete the LOOK section first, then place a small amount of each powder into a separate water cup, stir gently, and record whether it dissolved, did not dissolve, or was uncertain. Students take turns as Investigator and Recorder, switching roles halfway through; they complete drawings, color descriptions, and the results table on the mystery-powder recording sheet. Teacher circulates, checks that students are following each step, and prompts with “What did you observe?” rather than “What do you think it is?”

4. 22–28 min · Evidence-based predictions. Teacher displays the prediction prompt and models connecting a result to a claim: “I think Powder A is salt because I observed that it dissolved in water.” Students use their recorded evidence to predict the identity of all four powders and complete the sentence frame on the mystery-powder recording sheet. Students may mark “not sure” when evidence is insufficient; accuracy of reasoning is valued over correct guesses.

5. 28–33 min · Partner evidence share. Teacher projects the modified Rally Robin directions on the procedure and discussion slides. Partner A shares one observation, and Partner B shares a different observation; partners then explain one prediction and its evidence. Students listen for whether each claim includes a specific observation and revise their wording if needed.

6. 33–37 min · Reveal and analyze. Teacher reveals the answer key—baking soda, salt, sugar, and cornstarch in the prepared order—and asks students to compare their predictions with the results. Students mark how many identifications were correct, then discuss which powders looked alike, what the water test revealed, and whether any prediction changed after testing. Teacher emphasizes that a prediction can be reasonable even when it is not correct if it is supported by evidence.

7. 37–40 min · Exit ticket and close. Teacher distributes the final reflection area on the mystery-powder recording sheet and displays the closing prompt on the reveal, reflection, and exit-ticket slides. Students select the science skills they used—observe, test, record, or predict—and complete: “One thing I learned was…” Two or three students share responses before materials are collected.

Resources

• Four mystery powders: baking soda, salt, sugar, and cornstarch
• Four small labeled cups: A, B, C, and D
• Small cups of water
• Magnifying glasses
• Craft sticks or plastic spoons
• the mystery-powder recording sheet
• the mystery investigation slide deck
• Answer key kept by the teacher
• Paper towels and a waste container
• Crayons or colored pencils

Assessment

• During the investigation, check whether students follow the multistep procedure, distinguish observations from guesses, and record results accurately.
• Listen during partner sharing for a specific claim supported by evidence from the visual inspection or water test.
• Use the exit ticket to assess whether students can name a science-processing skill and describe a learning point. Review predictions and evidence statements for next-step instruction.

Differentiation

• Support students with a teacher-modeled example, enlarged step cards on the slides, and repeated gestures for LOOK, TEST, RECORD, and PREDICT.
• Provide sentence frames, word choices such as “white,” “grainy,” “smooth,” “powdery,” “dissolved,” and “did not dissolve,” and allow pointing, circling, drawing, or dictating instead of extended writing.
• For students who become overwhelmed, test two powders first, then add the remaining two. Pair students strategically and assign clear Investigator and Recorder roles.
• Offer dyslexia-friendly access through a clear sans-serif font, large print, high contrast, short directions, read-aloud instructions, uncluttered worksheet sections, and oral response options.
• Challenge advanced learners to identify which observation was most useful, explain why appearance alone was unreliable, or propose one additional safe test and predict what it might show.

Extension

• Students write a short claim-evidence-reasoning paragraph explaining their most confident identification.
• Students design a simple comparison table showing how appearance and solubility together improved their predictions.