Chemistry Target group: teachers For Chemistry, the most difficult subjects in teaching online were: ● Atoms ● Mixtures and pure substances ● Chemistry general ● Solution According to Chemistry teachers, the most difficult topic to teach online was Atoms, especially with regard to Ions, Ions subatomic particles, Atom model andElectronic chain. For Mixtures and pure substances the most difficult topics were: - Methods of separating pure substances from mixtures; - Physical and chemical changes of substances; -Distinction between pure substances and mixtures. In Chemistry General, Atoms and Molecules were considered almost equally challenging in teaching online. Finally, in Solution, Concept of solubility of substances and saturation of solutions is considered as the most challenging topic in online teaching, together withSolutions as examples of mixtures and distinction between solvent and soluteandFactors that affect the rate of dissolution of substances. 19