Go through the notes of chapter 2 from above link
https://www.learncbse.in/components-food-cbse-notes-class-6-science/

Children use the link given below to understand and write the notes for chapter 2: Components of Food (class 6)
https://www.learncbse.in/components-food-cbse-notes-class-6-science/ 

class 9

https://www.youtube.com/watch?v=apewLkLAR-U

follow this video to understand concept of speed and velocity

class 6

https://www.youtube.com/watch?v=Uzltty4LSIE
follow this link to understand international system of numeration

class 8

https://www.youtube.com/watch?v=fDWGY1FcKqo

follow this for pie chart 

class 7:

https://youtu.be/6DYtC7lrVuY

follow the above video to understand mean, median,mode