Friday, 26 May 2017

Blast off!

This week Class 5 made 'pop rockets' using film canisters and alka-seltzer tablets. 
After this, they used the test results to plan a new scientific enquiry to answer a question of their choice. Just for fun, we made it a competition - the person who designed the best investigation would get to carry it out at the end of the week. 
The children came up with lots of great questions to investigate and designed their own comparative and fair tests. 
The winning investigation was chosen because the child who designed it could recognise which variables needed to be controlled. 
On Friday (today) we carried out the winning investigation to answer the question: Will the size of the piece of alka-seltzer tablet affect how high the rocket goes? 
We controlled the variables (kept the same): the size and type of canister, the amount of water used, the time at which the tablet was dropped into the canister. This made it a fair test to ensure we could answer the question without these variable affecting our results. 
We needed to change the size of the piece of alka-seltzer tablet. We needed to use one quarter of a tablet in one canister, and one half of a tablet in another canister to be able to compare and see which one went the highest. 
We needed to measure which canister went the highest to answer our question. 
Before we carried out the investigation everyone made a prediction based on their scientific knowledge. 
In the end, everyone got to carry out the investigation. It was great fun and even better to be outside learning on such a beautiful day.
The results showed that the bigger piece of tablet made the canister go higher. We also observed that the canisters with the bigger pieces of tablet 'lifted off' before the canisters with smaller pieces. We concluded that the larger piece of tablet made the rocket go higher (and launch more quickly) because more carbon dioxide was released. The carbon dioxide gas filled up all the space inside the canister and continued to expand, forcing the lid off and the rocket to launch. 
Finally, we set the rockets off with a whole tablet! They went even higher, but we noticed that not all of the tablet was used up. This means that not all of the tablet was needed to launch the rocket. One half of a tablet is the optimum amount of fuel needed to launch the film canister rockets.