Fall Leaf Inquiry
Back in October, we spent a few days studying leaves. In Science we were learning about The Needs of Living and Non Living Things, so this tied in nicely with that unit. We had also been talking some about seasonal changes, and about the five senses.
We started out our inquiry with a relaxing walk through the forest. We brought a few things with us on our trip - a magnifying glass, a bag for collecting leaves, a clipboard, a leaf identification chart, and a worksheet and pencil for recording. As we walked through the woods, we gathered leaves and tried to identify some using the chart. We tried to find many different types of leaves so we had a variety to examine when we got home.
We also tried to take our time and pay attention to our five senses. Landon used the worksheet to record his observations using his senses. He recorded many of the things he heard, saw, smelled, and felt and tasted on our walk.
When we got home, Landon spent some time identifying and sorting his leaves. We talked about ways we could sort them - by type, by size, by colour, etc. Then we counted them.
Next, we talked about how and why leaves change colour. I had taken some simple Junior Non Fiction books out from the library to help with this, which we read together.
Then we did a simple chromatography experiment to look at the colours in each leaf. Chromatography is the separation of a mixture of substances. Through the process of chromatography you are able to see all of the pigments present in a leaf, separated. The different pigments are from different chemicals in the leaf. The molecules of the pigments are different sizes so they become separated as the different molecules travel different distances up the paper towel.
🍃 Chlorophyll gives leaves their GREEN colour and allows the leaf to capture energy from the sun through photosynthesis.
🍂 Anthocyanins make leaves RED. They are usually produced in the Fall.
🍁 Carotenoids make leaves YELLOW and ORANGE. They are present in the leaf all the time, but are hidden by the stronger green pigment.
In Fall, the days become shorter and provide less hours of sunlight, so plants prepare for winter by shutting down photosynthesis, causing the green chlorophyll to disappear from the leaves. As this happens, the leaves begin to reveal other colours that have been there all along but were hidden by the green pigment, as well as new colours created through new chemical changes.
MATERIALS:
• Leaves
• Absorbent paper towels
• Rubbing alcohol
• Glasses or jars
• Scissors or knife (optional)
• Wooden spoon or tool for mashing
1. We picked our three favourite types to do this experiment with.
2. Tear up about ten leaves of each type that you plan to use. The smaller the pieces, the better.
3. Put your torn leaves into their respective jars and label them. Then cover them with rubbing alcohol and mash them for about five minutes, until you see the alcohol change to a dark colour. Then leave them to soak in a dark place for at least 30 minutes.
4. Remove your leaf bits from the jars leaving only the coloured alcohol. Now let the liquid sit in a dark place longer until some of the alcohol evaporates. This may take overnight.
5. Fold each of your paper towels into a narrow strip - one for each jar. Now dip the end of one into each jar and watch as the pigmented alcohol climbs each towel. Then remove the strips and allow them to dry and darken.
You should be able to see multiple bands of colour on each paper towel, and these pigments have been sorted by their molecule size. You may observe colours on your strips that you hadn’t seen on your leaves. They were present on the leaf but had been hidden by other pigments.
Lastly as part of our Leaf Inquiry, we talked about what purpose leaves serve on a plant. Then we did another simple
experiment to examine how leaves “breathe”.
MATERIALS:
• An active leaf (it must be one that is freshly removed from a tree or plant)
• Lukewarm water
• Glass bowl
1. Fill your bowl with lukewarm water.
2. Submerge your fresh leaf in the water and place something heavy enough on top to hold it down. We used a spoon but a small rock would work as well. Now place your bowl in a sunny spot and wait!
3. Come back in a couple of hours and you will see small bubbles have formed around your leaf and the sides of the bowl. We used our trusty magnifying glass to get a better look at them 😉
Your leaf has been performing photosynthesis and those tiny bubbles are the oxygen it has expelled through the process. A leaf does not “breathe” like we do with lungs. People and animals need oxygen from the air and release carbon dioxide. A leaf takes in air through its stomata, using the carbon dioxide and expelling oxygen. This is one reason why plants are so very important to our Earth!
If you have a microscope at home, you can try this trick to get a close up look at these stomata! Otherwise there are plenty of great YouTube videos or websites where you can learn more.
We had a great time learning hands on all about leaves! And we hope you do too 🍃
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