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Lesson Plan

Plant Dyes

Summary: 
Extract dyes from plants. Make red cabbage dye and vary it's colour with acid/base. Use to dye fabric or wool. Test other plants for their dye colours. (To extend to other non-plant dyes, separate the dyes in marker pens.)
Science content (2016 curriculum): 
Biology: First People’s sustainable use of Living Things (K, 2, 3)
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: First People’s Materials/Separation methods (1, 6)
Chemistry: Physical Changes, Solutions, Mixtures and Separating (2, 4, 5, 6)
Chemistry: Chemical Changes (2, 7)
Procedure: 

Make red cabbage dye and experiment with how it changes colour in acid or base.
Use different red cabbage colours to dye cotton strips/cotton yarn, to later use for weaving.
Discuss how many plant colours vary with acid and base (as do colours in flowers).

Reveal the dyes in other plants by crushing them on paper, and learn about First People's use of plant dyes.

Additional dye activity (not plants):
Separate the dyes in felt pens using chromatography.

Definition of dye and pigment:
Dyes are colours dissolved in water to make a solution. A pigment, often used in paints, is a suspension of a solid in a liquid. See notes for more.

Notes: 

The colour in children's markers is a dye - a solution of coloured molecules in water. Permanent markers, dry erase pens and ballpoint pens are also dyes in a solvent. Paints are generally a pigment - a colloid of solid particles suspended in a liquid. Pigment-based art materials are more opaque than dye-based art materials.
Should be able to see the difference between a dye and a pigment under the microscope.

Brock used red cabbage to dye wool, then found dyes in other plants.

Grades taught: 
Gr 4
Gr 5
Gr 6
Teacher: 
Carla Mountali
Ingrid
Melissa Marshall
Teaching Site: 
Brock Elementary
ingridscience afterschool
Lesson plan originally developed and delivered: 

ingridscience aferschool, then Brock Elementary