Table 2.

Student responses to the open-ended questions in PhAT parts B″ and C″

	Fall 2008		Fall 2009
	Pretest	Posttest	Pretest	Posttest
Why is the tree you chose better?
Principle of parsimonya	0	32	0	78
There are less eventsa	1	31	7	33
Fewer is better/simpler/Occam's razora	0	34	2	24
Fewer marksb	0	34	12	10
Organisms with more similar traits grouped together	81	30	43	10
Arranged better/less complicated	32	32	28	4
Answer does not fit within these 6 categories	97	23	73	5
Why are the two taxa you chose closest relatives?
They share the most recent common ancestora	0	17	6	9
They evolved from/share a close or most common ancestora	3	10	8	9
Evolved from same ancestora	0	0	4	10
They are sister species (or taxa)	0	51	0	18
They share same/most characteristics/traits	153	127	93	88
They come off the same branch	22	4	16	25
Answer does not fit with the above 6 categories	33	7	38	5

^aAnswer received full credit.

^bAnswer received partial credit.