Potato Osmosis Simulation Lab Worksheet | Includes Statistical Analysis

A complete IB Biology osmosis investigation worksheet using an online simulation. Students collect realistic data, identify outliers, calculate % mass change, plot graphs with error bars, and run a statistical test — all in one lesson. No lab equipment required.

This 8-page worksheet guides IB Diploma Biology students through a full investigation into how NaCl concentration affects the mass of potato cylinders — using the free Teaching with Tech Osmosis Investigation simulation. Students design the experiment, collect realistic data with built-in biological variation and the occasional outlier, then process and analyse their results using free online tools.

It’s everything you need to teach the water-potential practical in a single lesson, with no consumables, no balances, no lab time — but with all the rigour of a real investigation.

★ WHAT’S INCLUDED ★

• Print-ready 8-page worksheet
• IBDP-level background on osmosis, water potential and solute potential
• Step-by-step instructions with annotated screenshots showing exactly what students should see at every stage
• Pre-built Variables Table (IV / DV / CV) ready for students to copy
• Spreadsheet workflow for % mass change, mean, standard deviation
• Outlier identification using the 1.5×IQR rule with box-and-whisker plots
• Graphing instructions including error bars and best-fit line
• Statistical test selection using a decision flow chart
• Three suggested extensions for differentiation and higher-attaining students

★ HOW IT WORKS ★

1. Students open the osmosis simulation (link inside the worksheet)
2. They pick their independent variable, lock the controls, and run 5 replicate trials at each NaCl concentration
3. They export the raw data as a CSV
4. They process the data in Google Sheets or Excel and identify outliers using the free TwT Statistical Analysis tool
5. They plot the results with error bars using the free TwT Graph Generator
6. They run a Pearson’s r correlation test to support their conclusion

All linked tools are 100% free, browser-based, and require no logins or installations.

★ TEACHING POINTS COVERED ★

• Definition of osmosis and partial permeability
• Water potential (ψ), solute potential (ψₛ), pressure potential (ψₚ)
• Hypotonic, isotonic and hypertonic solutions
• Identifying IV, DV and controlled variables
• Calculating percentage change in mass
• Mean and standard deviation as measures of central tendency and spread
• Outlier detection using box-and-whisker plots and the 1.5×IQR rule
• Plotting graphs with error bars
• Choosing and interpreting a Pearson’s r correlation test
• Estimating tissue water potential from the x-intercept of a best-fit line