Science Experiments: Why Do Leaves Change Colour?

Science experiments for kids are big in our home. My kids love them – and so do I. While teaching Kindergarten I made science experiments a priority. Kids are so naturally curious about the world around them and science experiments bring this learning fully to life! So my wee ones and I decided to do 5 Days of Science Experiments for kids. Today’s experiment: “Why do leaves change colour in the Fall?”

I thought there was no better way to start this than with my ABSOLUTE favourite science experiment OF ALL TIME (oh yes, I promise it is THAT GOOD!)

When asked by my daughter at age 3 (7 years ago!), “Why do leaves change colour?” I had no answer. I looked it up, found it too complicated for a 3 year old, but explained the best I could and let it be.

I was in Teacher’s College at the time, and wouldn’t you know a few weeks later we learned about (and did) a science experiment for kids about leaves changing colour. It made things so much clearer that I immediately did the experiment with my preschooler Madeline.

Please keep in mind this is my (limited) understanding having done the experiment and some research in that class. I’d love to share it with you. So ….

Why Do Leaves Change Colour?

Leaves contain Chlorophyll. Chlorophyll makes the leaves green and is so dominant that it covers up all the other colours in the leaves. To figure out what colour a leaf would be without the dominant chlorophyll colour, we can separate the colours by doing this science experiment.

This experiment is very simple and you likely already have everything you need:

Materials:

3 leaves (from the same tree)

Rubbing Alcohol

Jar

Plastic baggie (or plastic wrap)

Paper Coffee Filter

Small bowl or pan

Steps:

1. Have your child break the leaves into tiny pieces and put in the jar

2. pour rubbing alcohol over the leaves until they are just covered

3. mash and stir the leaves into the rubbing alcohol until the alcohol turns slightly green. Really give it a good mashing – this is key.

4. cover the jar with the baggie or plastic wrap and place the jar in a small bowl and pour hot water into the bowl.

5. leave (ha!) the jar in the water for 30 minutes, swishing the jar occasionally to stir the leaves a bit. The alcohol should be a very dark green (leave longer if needed). If you can resist, wait even 45 minutes or an hour.

6. Cut a strip in the coffee filter so the strip can reach the rubbing alcohol. Place it in the jar like this:

(We just cut a strip off the coffee filter and taped it to the edge of the jar)

7. The liquid will travel up the coffee filter and the colours will separate as the alcohol evaporates off the coffee filter. Let this happen for about an hour for the full effect. The leaves we used turn to a beautiful yellow in autumn.

So … Why Do Leaves Change Colour?

In this science experiment we used the rubbing alcohol and energy (hot water) to separate the colours. You likely saw green, and depending on your leaf type, maybe red, yellow, or orange. As we know, Chlorophyll gives leaves their green colour and is so dominant it hides the other colours in the leaves. But in the fall, chlorophyll in the leaves breaks down allowing the other colours to finally shine through and show their beautiful reds, yellows, and oranges.

I hope your kids will love this experiment as much as mine. Science is naturally so hands on and relevant to kids real worlds. Even if your wee one is very wee it may be worth giving this one a go. I did it with my Sam and we spaced out the wait time with his rest time. Even though he did not grasp everything I know he learned a lot!

Please consider liking us on Facebook so we can share more creative learning activities with you and your little ones! Thank you!