Developing learners’ speaking skills in the language classroom is one of the most demanding tasks that foreign language teachers are confronted with. The difficulty results mainly from the fact that the target language functions here as both the medium and the goal of teaching. Research shows that active involvement in communication in the learning process helps in improving language skills. The article discusses the role of classroom communication in learning both the first and the foreign language in the light of selected literature and offers a number of teaching guidelines for effective classroom practice.

This paper presents the results of tests of selected physical and mechanical properties as well as the chemical composition of two types of natural aggregates: porphyry and diabase, as well as artificial aggregate based on steel slags. Based on the conducted tests, it was established that the physical and mechanical properties of the artificial aggregate exhibit slightly lower parameters as compared to the results obtained for porphyry and diabase aggregates. However, this does not limit the possibility of using the aggregate based on steel slags, as according to the applicable WT-4 and WT-5 standards, it can be used in mixtures unbound to the improved subsoil and layers of the road foundation as well as road mixtures with hydraulic binders for each category of traffic load. The chemical composition of the aggregate based on steel slags differs from the chemical composition of the tested natural aggregates. The slags contain lower amounts of SiO2 and Al2O3, while the concentration of CaO and Fe2O3 is greater. Additionally, heavy metals have also been exhibited in the slags. However, it was established that the alkaline nature of the slags, which is affected by low sulphur content and a significant proportion of CaO, as well as the way the metals occur limit the possibility of heavy metals release and migration from slags. The tested steel slags may constitute a prospective material used in road construction.

The Cleveland Shale fauna represents a unique view of the time after a major Devonian extinction event

(Frasnian–Famenian) with the recovery of arthrodires (Placodermi) best represented by this most specious

North American fauna. This time was followed by an additional event (Hangenberg Biocrisis) leading to the

extinction of arthrodires (and all other placoderms). An understanding of the diversity and interrelationships of

North American arthrodires can aid our understanding of this critical time in vertebrate evolution. A new aspinothoracid

arthrodire Hlavinichthys jacksoni gen. et sp. nov. is described from the Late Devonian of northern

Ohio, U.S.A., which adds to our knowledge of this group. It provides a point of comparison to other members

of the fauna whose interrelationships are poorly known. A phylogenetic analysis supports an assignment of

Hlavinichthys jacksoni gen. et sp. nov. among the aspinothoracid arthrodires. This work has drawn attention to

the continued need for descriptive and phylogenetic analyses of this unique fauna. Decades old species descriptions

need revision along with preparation and description of new taxa. The work on Hlavinichthys jacksoni

gen. et sp. nov. here is one step in that process.