Vocabulary should be taught: Through planned lessons.
At home.
Through natural conversations and interactions.
Through both conversations and lessons.
To English language learners.

The third one

Explanation:

it is better for vocab to be taught through natural learning and lessons, instead of one or the other.

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

the independent variable, or the one that is intentionally manipulated is the speed.