The Montessori method recommends that children have 'concrete' physical experiences with concepts before trying to create more 'abstract' understandings.
This unique material - the 'Hand Boiler' - allows a child to have a (literally!) hands on experience with an interesting scientific concept; "Charles's Law".
Charles's Law refers to the idea that as gas is heated it tends to expand. A pre-school child might simply engage in the sensory experience of watching this principle occur before their eyes, while a primary school child could further investigate the mechanics behind this phenomenon!
As the child holds the base of the Boiler the heat generated by his/her hand is transferred to the gas inside. This gas expands and this displaces the liquid, pushing it upwards through the loops and into the top of the boiler.
As the gas cools down the liquid starts to slowly trickle back down again, filling the empty space left behind by the condensed gas. I love observing children as they patiently await the moment that the liquid has reached the bottom again...so that they can heat it back UP again!
During one of our explorations my pre-school children discovered that they could force the liquid down again more quickly by grasping the top of the Boiler. This creates the same effect (expanding the gas inside) but this time the gas expands at the top, thus pushing the liquid down. The children could then 'follow' the liquid down the glass, pinching the space just above the top of the liquid to help it move further and further down.
The Hand Boiler is also a uniquely attractive aesthetic object! It looks beautiful resting on a windowsill or shelf.
The Hand Boiler measures approximately 16cm in height, with the glass spheres at the top and bottom measuring around 4.5cm in diameter. They are available in four colours; Blue, Green, Purple & Red.
Please note: The Hand Boiler is made of extremely thin glass. This is necessary to allow the heat to transfer from the hand to the interior of the boiler (thicker glass would slow the process significantly). This does, however, mean that the glass is quite fragile. We therefore recommend careful supervision of any child who is handling/interacting with the Boiler. The Montessori method deliberately includes 'risk' as a method of helping children to learn self-control and respect for materials, but it is important that an informed adult thinks carefully about how to safely manage those risks. Please see our Safety Advice for more information.