When the Christmas holidays are upon us, and the Christmas treats have all been eaten and the presents have all been opened, and it’s 4 pm and already dark outside and everyone is going a little stir crazy, we’re here to provide you with a bit of inspiration – Christmas-themed science experiments!
Have you ever noticed that pine cones open and close their scales?
Pine cones are a key element of decoration at this time of year – you can find them on Christmas wreaths, Christmas trees and, if you’re lucky enough to have a fireplace, giving their pine aroma to a warming wintery blaze. These pine cones that we’re so familiar with are part of the female reproductive organs of the pine tree. The pine cone is made up of scales arranged in a spiral, with seeds on top of the scales. The main function of a pine cone is to keep a pine tree’s seeds safe. Pine cones close their scales to protect the seeds from cold temperatures and unfavourable conditions, and they open up and release their seeds when it’s warm and is easier for the seed to disperse and to germinate. We can perform a simple experiment to observe how this works.
- Take a pine cone that has its scales open like the ones on the left in the photo. Place it in the bowl with cold water and wait for an hour or so.
- Observe how the pine cone’s scales have closed up and the pine cone has become smaller. (Take a photo beforehand or keep an open pine cone nearby for comparison). This replicates what happens when the conditions are wet and shows how the scales keep the seeds safe inside the cone.
- Reverse the process by letting the pine cone dry in a warm place for a few hours or in the oven at 120 C/250 F for 10 mins (with adult supervision!).
When the cone is dry, try rolling it in a tea towel and tapping on a hard surface to see if there are any seeds that fall out. The seeds have a small wings that allow them to “fly” away from the parent tree by catching any wind.
For more explanation about this experiment, watch this video until 1 min 45 sec. For older or more curious scientists, keep watching until 4 min 46 sec to learn a bit more about the mechanics of the closing pine cone.
Is black pigment truly black? Find out with Christmas chromatography
Paper chromatography is a technique used in chemistry to identify the different components of a liquid solution, like the different pigments in dye. The different components separate as they travel through the paper because they travel at different rates, and by comparison with known chemicals it’s possible to identify what they are. We can use this technique to investigate the components of water-based markers and to create tie-dyed baubles for the Christmas tree.
What you’ll need:
- Washable markers – a range of brands, if possible. Include black and brown and other colours.
- Coffee filters or filter paper
- Small glass or container to rest the coffee filter on
- Container of water
- Christmas ribbon
- Thread or fine string
- Cut circles out of filter paper (we used coffee filters).
- Draw a dot, a line, or a series of dots in the middle of your filter paper with washable markers
- Place the filter paper on top of the glass or container.
- Using the dropper, add a few drops of water to the middle of the paper and watch the water and pigment soak outwards. Some markers (e.g. black) might separate into different colours, while others might show only one colour.
- Let the paper dry and then attach ribbon and thread to hang the ornaments from the Christmas tree.
Idea from Inspiration Laboratories
Plants are the chemists responsible for our favourite Christmas tastes and aromas
If that’s not enough Christmas-themed science for you, check out the YouTube channel of Vienna-based plant scientist, Eva Knoch: The Molecular Garden (@DermolekulareGarten). She makes short popular science videos about the incredible and diverse chemicals that plants make and that we encounter in our everyday lives, including an Advent Calendar with Christmas themed videos for each day of Advent. You can find out whether your delicious cinnamon baking might be poisoning you and whether brussel sprouts really are less bitter than when we were forced to eat them as kids. The videos are in German and come with English subtitles.