Active and passive

You will see sentences using active verbs and passive verbs in science. Sometimes you need to use passive verbs, but active sentences are easier to understand. Active verbs Use active verbs in sentences to give direct and clear information. Structure: Who does/did what. Examples: • I observe the chemical reaction. • He dissolves sugar in water. • She can use indicator paper to test acidity. • The reaction produced hydrogen gas. Passive verbs Passive verbs in sentences are sometimes more confusing for learners of English. Structure: Something is/are/was/were done by whom or what. It is possible not to include who did the action if it is not important who did it. Example: • The chemical reaction is observed (by me). • The sugar is dissolved in water (by him). • Indicator paper can be used (by her) to test acidity. • Hydrogen gas was produced by the reaction. Changing active to passive it, she, he Active Who/what verb What We measure the distance. She measures the distances. Passive What is/are + past participle Who/what SAMPLE

The distance is measured by us.

The distances are measured by them. Notice how the word order changes when you change active to passive.