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2. Research Method 
This research is developmental research (R&D) using ADDIE model. 
2.1. Subject of research 
Subject of this research were all of 2
nd
year students (64 students) in science and mathematics programe 
in SMA Negeri 2 Sleman.
2.2. Development of learning devices 
The development of learning devices includes: student activity sheets, lesson plan, and research 
instrument used to measure the student’s critical thinking skills. The learning devices were developed 
by the researcher using ADDIE model and had passed validity test with valid result by the expert 
judgement.
2.3. The instrument, data collection techniques, and data analysis techniques 
The instrument for collecting data were a test (pretest and posttest) and critical thinking skills
observation sheet. Pretest and posttest consisted of essay question that adjusted to the indicators of 
critical thinking and validated by the expert. The teaching and learning process were carried out for 4 
meetings supported with learning deviced that had been developed. The learning steps which used in 
this research based on Hmelo-Silver syntax consisting of problem orientation, formulate and analyze 
problem, generater hypotheses, identify knowledge deficiencies, apply knowledge, and abstraction [16]. 
2.3.1. Analysis of critical thinking test 
Student’s learning outcomes were analyzed descriptively using N-gain indicator and analyzed 
parametrically using T-related sample test. Student’s learning outcomes categorized according to 
Setyowati & Mosaik [17] which presented in Table 1. 
Table 1. Level of critical thinking
Score 
Criteria 
81.25- 100 
Very Critical 
62.50- 81,25 
Critical 
43.75- 62,50 
Less Critical 
25.00- 43.75 
Very Less Critical 
 
2.3.2. Analysis of observation sheet 
Critical thinking skills observation sheets were analyzed by calculating the percentage of student’s 
critical thinking skills at each meeting. The percentage of student’s critical thinking ability is calculated 
by the formula: 
𝑇 =
𝑇𝑜𝑡𝑎𝑙 𝑠𝑐𝑜𝑟𝑒 𝑜𝑓 𝑖𝑡𝑒𝑚 𝑡𝑜−𝑖
𝑇𝑜𝑡𝑎𝑙 𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑠𝑐𝑜𝑟𝑒
𝑥 100% 
The criteria are according to Widoyoko [18] : 
80 < SA ≤ 100 : very good 
60 < SA ≤ 80 : good 
40 < SA ≤ 60 : good enough 
20 < SA ≤ 40 : poor 
2 ≤ SA ≤ 20 : very poor