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Basic Tree Thinking Assessment 1 (BTTA 1)


The Basic Tree Thinking Assessment 1 (BTTA 1) is designed to evaluate your tree-thinking skills in majors undergraduate biology curriculum concentrated on evolutionary biology. Specific topics include the theory of evolution by Charles Darwin.


The BTTA 1 is commonly administered in introductory biological evolution college courses.

Typical Performance

We do not know of any published results with typical performance. As the LASSO platform collects more data, we will be able to offer better guidance on student performance.

Example question:

By reference to the tree above, which of the following is an accurate statement of relationships?

  1. a)  A green alga is more closely related to a red alga than to a moss
  2. b)  A green alga is more closely related to a moss than to a red alga
  3. c)  A green alga is equally related to a red alga and a moss
  4. d)  A green alga is related to a red alga, but is not related to a moss 


The BTTA 1 was originally developed in 2005. The validation has focused on college students but spans several institutions. Items were examined for difficulty, discrimination, and assessment reliability. Relevant articles are listed below:

      Baum, D. A., Smith, S. D., & Donovan, S. S. (2005). The tree-thinking challenge. Science, 310(5750), 979-980.


We recommend using Google Scholar and the citations listed under validation to find articles of interest.

Example LASSO Report

Please follow this link to our example report for concept inventories.