For understanding information and explanation while learning about the nature (so: biology, chemistry, physics...) via ICT the student must have developed skills implied in the terminus 21st century literacy, which implies so called computer literacy, media literacy, information literacy and above all visual literacy. Visual literacy in needed for perception of visual data in the multimedia text, to understand them and to interpret them correctly. But that is not all, for reading longer texts where words and images have an (equal) important role the student needs metacognitive strategies and specific metacognitive strategies implied in the conception of new literacy's too. This new and old literacy and new and old metacognitive strategies must be taught in the 21st century school in the frame of mother tongue lessons and in the frame of science lessons.