Two conceptual models of monitoring acquired knowledge and competencies of experimental HE programs were applied. First refers to the school year 2007/2008 when experimental and control schools were included and the second one in the school year 2013/2014 when the whole school population was involved in experimental implementation. Therefore, first compares in achievements was between students exposed to the HE program in duration of one school semester (approximately 5 months) and those who did not attend. Second evaluation model compared two time points, before and after program implementation, for the same students all involved in the HE program. In analysis and result presentation descriptive and inferential statistics were used: frequencies and percentages, means and standard deviations, t-test as well as related graphical tools (bars, diagrams, etc.).

Results In the first evaluation, initial knowledge test in HE was administered to the 1.123 students of 5th grade. 70,5% students (N=792) were in experimental program and 29,5% (N=331) were in the control schools, not attending the program. This test had 38 multiple choice items and 34,5 maximal points. Difference in arithmetical means between experimental and control group schools was only one point in favor of students who attended experimental program and was not statistically significant. The conclusion was that the program did not effected knowledge of 5th grade students who attended it. In the second evaluation test had 26 multiple choice items and 26 maximal points. In the first knowledge testing (N=1.400), in the beginning of program lessons, average score was 17,5 points and in the second testing (N=1.373), at the end of the program, average score was 19 points. The results show statistically significant difference (p<0,01) in students’ knowledge in-between measurements. Conclusions Both generations of 5th grade students’ who attended experimental program in HE were introduced to new contents for the period of 12 school hours. Taking into consideration that during the second evaluation, generation 2013/2014, significant difference in knowledge attainment was measured, we concluded that the different curriculum content was the key reason for altered result. Number of teaching hours, duration of the program and teaching methods were comparable and the same. Positive results in knowledge testing in the second generation of experimental program implementation and evaluation were the basis of permanent instalment of HE contents in Croatian elementary and secondary schools curriculum in the form of inter-curriculum contents.