Greetings from Madrid (Spain)

[Hostos]

Hi everyone. My name is David.

On March 21, 2018 the fourth grade students (8 years old) from the Primary School “Eugenio Maria de Hostos” (Madrid, Spain) has done an activity with water rockets with the aim of experimenting and learning about the scientific method.

The data and results of the activity were:

Experimental data:

15 water rockets
identical design
2 l of capacity
cork stopper in the bottles
Manual floor bicycle air pump.

Five of them with 250cc of water,
another five with 500cc of water,
and the last five with 750 cc of water.

Results: (Average of 5)

250 cc of water ………. 28,1 meters high
500 cc of water ………. 30,7 meters high
750 cc of water ………. 27,4 meters high

We have had a very pleasant morning and I think that the students have understood the scientific method in a fun way.

[Hostos]

Sorry I made a mistake. Fourth grade is 10 YEARS OLD.

[anachronist]

I was going to say, your 8 year old fourth graders are pretty advanced kids!
I was 9 years old in fourth grade.

Your students learned that there is an optimal amount of water to fill the rocket. The optimal amount depends on initial pressure and the empty mass of the rocket. Too little water and you don't have enough reaction mass to gain much altitude, too much water and the rocket is too heavy to lift its own weight. I have found, for 100 psi pressure with a 2 liter rocket weighing less than 200 grams, about 500-600 ml of water works best.