Turn KS3 Science into a realistic STEM workplace investigation. Students take on the role of forensic technicians in a fictional missing-prototype case, analyse ink evidence using paper chromatography, interpret chromatograms, calculate Rf values and write carefully supported scientific conclusions.

Suitable for: Years 7-9, Chemistry (mixtures and separation), STEM enrichment, careers education, science clubs and cover lessons.

Duration: Approximately 60 minutes using printed evidence, or up to 90 minutes when running the optional practical (adjust for your class).

• 15-page student workbook with a full-page illustrated front cover and branded back cover (14 original workbook pages plus back cover).
• 7-page teacher guide and full answer key, including safety, differentiation, worked calculations and suggested responses.
• 2-page quick-start guide showing practical and no-equipment delivery routes.
• 24-page combined master PDF, containing the entire workbook, teacher guide, quick start and final back cover.
• Fictional case file, evidence register, chromatogram interpretation and analytical report task.
• Paper chromatography apparatus, practical method, investigation record and printable model chromatography data.
• Rf worked example, guided calculations, reliability questions and extensions.
• Forensic careers, STEM skills and reflective tasks.

Two delivery options: Run the supervised chromatography practical with suitable equipment and a local risk assessment, or use the complete printed evidence set without laboratory equipment.

Students will be able to:

• Describe the role of a forensic technician and identify relevant workplace skills.
• Explain paper chromatography, including the mobile and stationary phases.
• Compare separated ink components and calculate unitless Rf values.
• Use evidence to support conclusions without overstating certainty.
• Discuss limitations, contamination, evidence records and possible follow-up tests.
• Connect chemistry, maths and scientific communication with STEM careers.

Teacher benefits: fully structured tasks, accurate model data, complete answer guidance and both practical and printable pathways.

Important: The scenario and the chromatograms are fictional teaching models. A similar ink pattern cannot prove who wrote a note. The downloadable resource consists of four PDFs.