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Science · Year 7

Active learning ideas

Separation Techniques: Chromatography

Active, hands-on chromatography lets students directly observe how mixtures separate based on solubility and affinity. When they handle real inks and pigments, they connect abstract concepts to visible, measurable results faster than with diagrams alone.

ACARA Content DescriptionsAC9S7U06
30–50 minPairs → Whole Class4 activities

Activity 01

Experiential Learning30 min · Whole Class

Demonstration: Basic Ink Separation

Demonstrate by drawing a dot of black ink on filter paper, rolling it into a cylinder, and placing the bottom in water. Students observe and sketch band formation over 20 minutes. Discuss why colours separate based on solubility.

Explain the principle behind chromatography for separating mixtures.

Facilitation TipDuring the Demonstration, keep the solvent level low so students see the solvent front rise without flooding the paper.

What to look forOn a small card, ask students to draw a simple diagram of their paper chromatography setup. Have them label the stationary phase, mobile phase, and at least one separated ink color. Then, ask them to write one sentence explaining why the colors separated.

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Activity 02

Experiential Learning45 min · Pairs

Pairs Lab: Marker Chromatography

Pairs select washable markers, spot paper strips, and test in water or alcohol. Measure distances travelled by each colour to calculate Rf values. Compare results across pairs to identify patterns.

Design a simple paper chromatography experiment to separate ink colours.

What to look forPresent students with a pre-made chromatogram showing separated ink colors and their corresponding Rf values. Ask them to identify which ink was the most soluble in the mobile phase and justify their answer based on the Rf values.

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Activity 03

Experiential Learning50 min · Small Groups

Small Groups: Plant Pigment Extraction

Groups crush leaves in alcohol, spot the extract on paper, and run chromatography. Identify green, yellow, orange bands. Record observations and link to photosynthesis pigments.

Analyze how different properties of substances affect their separation in chromatography.

What to look forPose the question: 'Imagine you are trying to separate the pigments in a leaf. What factors would you need to consider when choosing your stationary and mobile phases? How might these choices affect your results?' Facilitate a brief class discussion.

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Activity 04

Experiential Learning35 min · Individual

Individual Challenge: Mystery Ink

Each student tests an unknown ink mixture on paper with different solvents. Predict and verify component colours. Share findings in a class gallery walk.

Explain the principle behind chromatography for separating mixtures.

What to look forOn a small card, ask students to draw a simple diagram of their paper chromatography setup. Have them label the stationary phase, mobile phase, and at least one separated ink color. Then, ask them to write one sentence explaining why the colors separated.

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Templates

Templates that pair with these Science activities

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A few notes on teaching this unit

Teachers should model careful spotting, solvent choice, and measurement to build precision. Avoid rushing through setup; let students repeat trials to see reproducibility. Research shows that concrete, multi-sensory experiences strengthen memory of abstract concepts like polarity and adsorption.

Students will confidently label the stationary and mobile phases, measure distances travelled by colours, and explain why components separate at different rates. Clear diagrams, correct Rf calculations, and reasoned justifications show successful learning.


Watch Out for These Misconceptions

  • During Marker Chromatography, watch for students assuming all colours in a marker move at the same speed.

    Ask pairs to compare distances travelled by each band and calculate Rf values. Have them present one surprising result to the class to challenge the misconception through evidence.

  • During Plant Pigment Extraction, listen for explanations that chromatography creates new colours.

    Have small groups track original dye mixes on a reference strip alongside their leaf extract. Encourage them to note unchanged hues in a shared table to reinforce that separation reveals existing components.

  • During Marker Chromatography or Mystery Ink, observe whether students automatically use water as the only solvent.

    Set up rotation stations with water, isopropyl alcohol, and acetone. Students must justify their solvent choice after testing each one, linking polarity to observed movement.


Methods used in this brief