PSOW – Practical 2.1G The Lincoln Index with Teacher’s Notes

Description

IB ESS Practical 2.1G: The Lincoln Index

Teach capture–mark–release–recapture without handling a single animal, using this engaging classroom simulation of the Lincoln index.

In this practical activity, scraps of colored paper scattered across quadrats represent populations of a fictional genus of mobile organisms, Charta. There are five species, each with its own Latin binomial name, such as Charta roseus (the pink charta) and Charta caeruleus (the blue charta). Students are also asked to work out what these names mean.

Students “capture” organisms using a loop of masking tape wrapped around a fingertip. The simulation follows the real field method step by step:

• Capture: collect as many organisms as possible in 30 seconds, count each species, and mark every captured individual
• Release and mixing: return all organisms to a container and shake it to redistribute them, just as marked animals disperse back into a population
• Recapture: repeat the capture, counting the total recaptured and how many were already marked (dimming the lights makes it harder to target marked pieces)
• Estimate and check: calculate a Lincoln index estimate for each species and the whole genus, then count the true population and calculate the percentage error

Students then combine data with classmates so they can compare estimates across several sampling areas.

Because the true population can be counted, students can see directly how accurate the Lincoln index is. They can also see when and why its assumptions break down.

IB ESS Internal Assessment Skills

This activity is assessed using IB ESS Internal Assessment Criteria D: Treatment of Data and F: Evaluation, and the full rubrics are included. Students must:

• Present data for all trials, their population estimates, and percentage errors, with the full Lincoln index calculation shown for at least one trial
• Evaluate the specific limitations of the simulation that affected accuracy, and suggest an improvement addressing the most important one
• State the assumptions of the Lincoln index and describe unresolved questions about applying the method to real populations of mobile animals

The activity is strong preparation for Criterion F, because the gap between estimated and actual populations gives students concrete, specific limitations to evaluate. Examples include incomplete mixing and the tape capturing pieces by position rather than at random. The teacher’s notes also encourage discussion of the animal welfare questions raised by marking real animals.

Ideal for

• Teaching capture–mark–release–recapture
• Calculating Lincoln index population estimates
• Exploring the assumptions of the Lincoln index
• Calculating percentage error
• Teaching sampling of mobile organisms
• Practicing binomial nomenclature
• Low-cost classroom ecology practicals
• Preparing students for the IB ESS Internal Assessment

Digital download. No physical product will be shipped.