Are NCERT science books good for class 6?

The books are good from the point of view of doing activities and practicals which help to further clear the concept

Why do we describe the people who lived in the subcontinent as early as two million years ago as hunter-gatherers?

This is because they did not lead a settled life and were always on the move. The food they ate was not cultivated, it was either “gathered” Or “ hunted”.

what is wind

Wind is the movement of air. Since air contains a number of gases, wind is the movement of gases on a large scale.