Question

the teen wanted to see how he might reduce the surface tension of water. that would break up the bridging over the pores, he explains. then, the water could flush through and rinse out the dirty substances.
7 nathan didnt have a lot of fancy equipment to work with. that didnt stop him. to measure surface tension, he gathered a large plastic syringe, some tubing, a kitchen scale - and of course some water. if a water droplet has a high surface tension, it holds together longer - and gets bigger - before a drop breaks apart. nathan filled his syringe with water and slowly pushed it out over the scale. bigger drops have more surface tension. so by weighing his drops, the teen could find out if changes he made to the water increased or decreased the surface tension.
8 nathan started with drops of water that had different temperatures. as water gets hotter, the molecules in it move faster. the teen hypothesized that this would make it harder for the water to form a film on the surface and its surface tension would decrease. he tested water at 5°, 15°, 20°, 35° and

1. what key idea about experimentation do the details in paragraph 7 support?

experimentation requires careful timing to ensure accuracy.
experimentation needs to be conducted in a scientific laboratory.
experimentation does not necessarily require expensive lab materials.

Explanation:

The text in paragraph 7 details Nathan's experiment - he used a plastic syringe, tubing, and a kitchen scale to measure surface tension. He filled the syringe with water and made observations as he dropped water. The emphasis on careful timing to ensure accuracy in measurement is the key idea.

Answer:

Accuracy in experimentation requires careful timing to ensure proper measurement.