Paper • open access

Table 3. Statistics data description score of student’s critical thinking skills 
 
N 
Minimum Maximum 
Mean 
Std. Deviation Variance 
Pretest 
64 
10.00 
55.00 
29.5703 
10.51789 
110.626 
Posttest 
64 
54.00 
83.30 
70.3542 
7.16612 
51.353 
Total
64 
These data shows an increase in the average score of student’s critical thinking skills. In the pretest, 
the average score is 29.57. While in the posttest, the average score is 70.35. This result shows that 
problem-based learning approach effective to develop student’s critical thinking skills. 
3.4. Result of N-Gain analysis of student’s critical thinking skills 
The result of N-Gain score are presented in Table 4. 
Table 4. N-Gain analysis of critical thinking test 
Aspect of critical thinking 
skill 
Average 
score of 
pretest 
Average 
score of 
posttest 
N-gain 
Criteria 
 
 
 
 
 
Analyzing 
29.33 
78.96 
0.70 
High 
Interpreting 
30.37 
46.87 
0.23 
Low 
Concluding 
31.25 
91.4 
0.85 
High
Evaluating 
25.78 
97.91 
0.95 
High 
All aspects 
29.27 
78.79 
0.69 
Moderate 

---

The International Seminar on Bioscience and Biological Education
IOP Conf. Series: Journal of Physics: Conf. Series 1241 (2019) 012020
IOP Publishing
doi:10.1088/1742-6596/1241/1/012020
6
Each aspect of critical thinking skills has different gain score. Overall, the N-Gain score of each aspect 
of critical thinking skills is increasing with a moderate category. Altough, the aspect of interpreting has 
a minimum improvement. This is because there are not many cases of the immune system that can 
display research data that suitable for high school students.
3.5. Result of Paired Sample T-test 
The pretest and posttest data were analyzed using paired data tests with data normality tested first, as a 
prerequisite for further testing carried out parametric or nonparametric [19].