This experiment will amaze kids – and even adults! It is so easy and almost magical to watch. I love doing science for kids and watching kids become fascinated and inspired by science experiments. This is one their favourites – and mine!
When introducing this experiment, I often talk about swimming pools and the yucky stuff that can grow in them if they are not taken care of. Some children mentioned that they had seen a parent test their pool before with a little strip that they dip in the water. This is a great example for this experiment and gives it a real world connection.
Today, we are testing the ph level in water. We can see the level change from an acid to a base right before our eyes! This can get a bit complicated for kids, but the hands-on experiment will give them a chance to learn a bit about acids and bases.
If you are working with older kids, you can call this a pH indicator, but magic water just sounds like more fun.
- Purple/Red Cabbage
- Blender (Optional)
- Baking Soda
One of the great thing about this science experiment is that the materials are probably materials that your children have seen and likely handled before. I always remind my children that in science we use our senses to observe, but not our sense of taste. I would suggest the same for this experiment, but I do like that the materials are all ones kids are familiar with.
When I did this science experiment at school, I did it in a kindergarten class. To say it was exciting was an understatement. I had each child do the experiment, but it could also be done as a big group with an adult showing the steps and reaction. Do what works for you.
Start by chopping up some purple cabbage. Once cut, put it into warm water. Roughly one cup of cut cabbage will work. You can either let it sit for 10-15 minutes, or you can put it into a blender. (Avoid having children use the blender. My students enjoyed watching their water change colour with the cabbage.)
Next, use a strainer to separate the cabbage from the water. You will be left with purple cabbage water. It is a really beautiful colour!
Once your magic water is ready, you are ready for the magic!
Take a small amount of vinegar. Ask kids what they know about vinegar. What does it taste like? What face do you make when you have eaten something with too much vinegar on it. We can say that vinegar is acidic – just like lemons!
Have children guess what they think is going to happen when you add the vinegar to the purple cabbage water. Add roughly 1/4 cup for every cup of cabbage water you are adding. Pour the vinegar into the water.
Make sure to watch closely because it changes quickly! Once you add the vinegar it changes the water from purple to pink. Or neutral to acidic. The vinegar acts with the cabbage water and changes it.
Kids will love the fact that you added a clear liquid to purple water and it turned pink! The pinker it is the more acidic it is.
The acidic water is red/pink and you will know the water is neutral when it is purple/blue. This is a great way to show kids that liquids can look the same (like water) but behave very differently and have different properties.
Science for kids can be very exciting and hopefully create some extra interest and curiosity in learning about the world around them. This experiment was a hit with my students, but they really wanted more once they had changed their water to pink.
You can build on this activity by changing the water back and forth with baking soda. When the water is pink, it is acidic. So if we add something acidic it can change it more pink, depending on the acidity of the liquid.
However, if you want to change it back to purple or neutralize the acid, you need to add a base material, such as baking soda. (Some children may be able to relate to this because some people add baking soda to their pool to help neutralize it.)
When the liquid is pink/red add a few tablespoons of baking soda to your water. It will fizz a bit (vinegar and baking soda create a chemical reaction) but then the colour (and acidity) will change to purple/blue.
What happens if you add more vinegar again? What about lemon juice? Try adding a bunch of baking soda.
You can add vinegar to the blue water and turn it back to red. By doing this you are turning it from a base to an acid again – which we can see by the colour.
Children will have fun changing their colours back and forth between red and blue and testing what happens if they only add a small amount of vinegar or baking soda versus a lot.
You can have a lot of fun with this science for kids at home, or in the classroom. As with all science experiment always have an adult supervising. Also, always make sure that children understand that chemistry and mixing different liquids together can be fun, but it can also be very dangerous.
I encourage you to try out this experiment with children of all ages, but as a parent and teacher, I also suggest that as you do the experiment that you take the opportunity to talk to kids about science safety and not mixing chemicals and other things they find around the house or classroom. This way science remains exciting and safe!
Looking for More Hands-On Activities?
If you like the magic water activity, you will love some of our other favourite science and learning activities. All of my activities have been done with children and are kid approved!