This is the start of a road map for the effective introduction of inquiry-based learning in chemistry. Advantages of inquiry-based approaches to the development of scientific literacy are widely discussed in the literature. However, unless chemistry educators take account of teachers' reservations and identified disadvantages such approaches will never have the place they deserve in the everyday teaching of chemistry. If circumstances do not allow for complicated and open-ended inquiry tasks, simpler and more structured inquiry-based tasks may be used. As a first step, teachers could be asked to modify and adapt established ‘step-by-step’ instructions to practical activities which require some stages to be designed by the students. If this happens only a few times in a school year the question arises about its effectiveness to develop experimental design skills and to reinforce knowledge and ideas taught in chemistry lessons. The present study describes the results of an empirical research project aimed to finding the answer. Modification of step-by-step practical activities as described requires limited time and effort, yet the results suggest that many students benefit from this approach.

The results of an earlier empirical research study on modifying ‘step-by-step’ instructions to practical activities requiring one or more steps of the experiments to be designed by students initiated a longitudinal study to investigate the effectiveness of the approach for younger students and over a period of time. The longitudinal study that followed took the form of a four year research project that began in September 2016. Over 900 students have been involved. All were 12–13 years old in the beginning of the study. Each year they spend six lessons carrying out practical activities using worksheets we provide. This paper reports the findings of the first year, when the participating classes were allocated to one of three groups. Group 1 was the control group. Students simply followed the step-by-step instructions. Groups 2 and 3 were experimental groups. Group 2 students not only followed the same instructions, but also had to complete experimental design tasks on paper. Group 3 students followed the same instructions, but one or more steps were incomplete and students were required to design these steps. The impact of the intervention on the students’ experimental design skills, disciplinary content knowledge and attitude toward chemistry is measured by structured tests. After the first school year of the project it was clear that the type of instruction only had a weak significant positive effect on the results of the Group 2 students’ disciplinary content knowledge. No significant effect of the intervention could be detected on the changes in the students’ grades and attitudes toward the subject, which only seemed to depend on the ranking of their schools. This paper provides the interesting details of the results of the first year (pilot) of the research and discusses changes to the approach that have been made for the remaining three years of the project.

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The discriminating efficiency of pyridino- (1), pyridono- and thiopyridono- (2), phenazino- (3), and acridino- (4) 18-crown-6 hosts as well as pyridino- (1) and phenazino- (3) 18-crown-6 hosts with allylic moieties attached either to the macrocyclic ring [X=CH-CH(2)-CH=CH(2) or C(CH(2)-CH=CH(2))(2)] or to the heterocyclic subunit was probed by circular dichroism (CD) spectroscopy using enantiomers of alpha-(1-naphthyl)- ethylamine hydrogen perchlorate (1-NEA). The CD spectra of the diastereomeric complexes as well as the difference and sum of the spectra were analyzed. Titration experiments were also performed monitored by CD or UV spectroscopy. The CD- and (1)H NMR-based enantiomeric preferences were compared. CD spectroscopy showed that the relative stability of heterochiral [(R,R)-host/(S)-guest or (S,S)-host/(R)-guest] complexes generally exceeds that of homochiral [(R,R)/(R)-or (S,S)/(S)] complexes. Bulkier substituents (R=iBu, sBu or tBu) decrease complex stability but increase the discriminating power of the host. According to (1)H NMR titration, attachment of one allylic linker group in position X of the macro ring [(S,S)-1b, (S,S)-1e] changes the discriminating preference (from heterochiral to homochiral) of the parent hosts (S,S)-1a and (S,S)-1d. This change of discriminating preference was not reflected in the CD spectra. Host (S,S)-1g with an allyloxy linker group in position gamma of the pyridine ring gives CD spectra which clearly reflect the high discriminating power and enantiomeric preference of the host. The exciton-coupled circular dichroism (ECCD) spectra of the 1-NEA complexes of phenazino and acridino hosts allow reliable determination of the enantiomeric preference by comparing the A values of the exciton couplets. An allylic group appended to the macrocyclic ring or the N-containing heterocyclic subunit allows for the attachment of the chiral discriminator to the solid matrix of a chromatographic sorbent and also serves as a spectroscopic label of the host. CD spectroscopy is a simple and rapid method, providing qualitative information on enantiomeric discrimination. It can be of great help in designing and testing new host molecules.

This paper reports the findings of the second and the third year of a four year longitudinal empirical research into the modification of ‘step-by-step’ instructions to practical activities which require...