This funny experiment for kids is a an excellent way for your children to exercise scientific experiments, comparable to the ones castle will carry out at school.

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By observing how some rocks float on water and also why some sink, introduce your son to the principle of density and how things like boats float. It additionally teaches some requirements of scientific experiments, such together fair tests and also writing predictions.

Step-By-Step overview To command The Experiment


1 - list Of devices And good Materials to Use

What equipment you"ll need:

A deep bowl of water- ideally see-through so girlfriend can conveniently observe the rocks sink to the bottom.

A timer

Pumice rock - this volcano rock can be uncovered in beauty, beauty shops or on Amazon, as it"s usually additionally used to scrub feet! simply make certain the pumice stones room real and natural volcano rock.

Smaller piece of volcano pumice - this deserve to be do by break up bigger pieces the pumice.

A range of various rocks with various properties and sizes - You can find great selections the rocks ~ above Amazon, or you might find part rocks on your walks. The benefit of buying rocks is the it"ll speak the type of rock on the description, even if it is it"s sedimentary, igneous or metamorphic. However, you might also be maybe to work out the form of rock by feather it increase online.

2 - write Down your Predictions

It"s always a an excellent learning experience for your child to write down predictions before a scientific research experiment, therefore you deserve to compare them come your results afterwards.

One thing world often predict prior to the experiment is the mass and size have an influence on whether the object floats or not, as opposed to the density. As such using a great range of sizes of pumice is a good idea come highlight that the thickness of an item is the main driving variable of whether something floats or not, no the mass.

3 - placing The Rocks and also Pumice right into Water

Once you have gathered her rocks and equipment, girlfriend are ready to begin your scientific research experiment to uncover out i beg your pardon rocks float and also which persons sink!

To begin, simply hold the absent on the surface on the water. Let go of the absent as soon as you let go of the rock, and also stop the timer if and when the rock reaches the bottom the the water. It might be less complicated for girlfriend to host the timer when your son releases the rocks.

Repeat this procedure three times because that the very same rock to get specific average and also then repeat this for each rock.

4 - Recording your Results

Write down a table with five columns. The number of rows will count on the number of rocks you have actually chosen to test; encompass one heat for every rock.

The an initial column should be title "Did the absent float Y/N", which will certainly be a basic yes or no answer. The second, 3rd and fourth columns need to list the time it took because that the absent to sink come the bottom that the bowl. Then the 5th column must be the typical of the 3 test times.

If the pumice floats for an ext than 30 seconds, just write N/A while columns.

5 - writing Your Conclusions

Once you have actually your table the results, you can write out your findings. Ask yourself the adhering to questions: i beg your pardon rocks float? how long did it take because that rocks come sink come the bottom? does the size and weight that the pumice influence the result? room density and also mass related?

The science Behind The Results

Density is the main factor that identify whether things floats or not. An object that has actually a greater density than water will sink and things with a lower density will float. Generally, solids space denser than liquids, i m sorry is why most of the rocks sank.

But cave on, the pumice is solid, therefore why did that float?

What you have most likely found from her experiment was that only the pumice stones float on water. Pumice rock is formed when a volcano erupts and the lava instantly come into call with the water. The lava is cooled by the water quickly and is solidified into pumice with several air balloon trapped inside. Wait is less dense than water i m sorry is why you watch bubbles rise. Pumice stones have sufficient air pockets for it come float.

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This concept helps define how boats float. Watercrafts are solid and also use products that room denser than water, yet they are made in a means to float. Their hollow forms ensure there is sufficient air come float, lot like the pumice.

Additional more Related experiment Your kids Can Try


You can conduct more related experiments by testing more objects. Shot objects of different sizes, shapes and also materials and also follow the same measures as above. Research right into why part materials and objects float and also what properties make them execute so. Every one of this is great science experience!