This is a really fun science activity for kids. It’s easy, cheap and brightly colourful! This activity explores the density of liquids all while using commonly found house-hold items. There are a few adaptations for younger kids that we have listed for this activity as, just because this activity requires skill and patience, they shouldn’t miss out!
How is this a science activity?
This activity explores different densities of liquids. It uses 4 different mixes of sugar and water to show that they behave and display different properties based on their densities depending on the amount of sugar we add into each mixture.
For a scientific inquiry we need variables (independent, dependent and control). Here, we are changing the quantity of sugar in the mixtures (known as the independent variable). The dependent variable is usually something measurable that we can record. However, the results of this science activity are more observational than quantitative as it produces a column of water with bands of different densities.
Some science activities, like this one, are more about showing the actual science principles and phenomenon of what is happening. Other science activities can show both the scientific principles and the scientific process like our racing rainbow activity.
However, it’s interesting to note that this activity does incorporates mathematics as we add in the sugar to each mixture and technology in the form of a syringe to disperse the liquids (don’t forget that technology doesn’t have to be electronic).
What do I need?
- Water – 4 cups
- Sugar – 12 tablespoons
- Food colouring (4 different types)
- 4 x Milk bottles/cups
- 4 x Stirrers – we used wodden popsticks
- A syringe or straw
- Shot glass
How to do it?
Here are the steps to follow:
- Fill each milk bottle with the same amount of water.
- Add a drop of food colouring to each milk bottle. Ensure that these are different colours for each bottle.
- Stir the food colouring in the water.
- Now, you will add in sugar to 3 of the different coloured bottles – keeping the first bottle with no sugar.
- Add in 2 tablespoons of sugar to the second bottle and stir it until all of the sugar dissolves completely.
- Add in 4 tablespoons of sugar to the third bottle and stir it until all of the sugar dissolves completely.
- Add in 6 tablespoons of sugar to the fourth bottle and stir it until all of the sugar dissolves completely. This may take some time. Be patient!
- Now, you will use the syringe to transfer the liquid from these bottles into the shot glass.
- Add in the 4th mixture first (ie the last bottle with 6 tablespoons of sugar). Add in 3 filled syringes.
- Next, add in the 3rd mixture (ie the bottle with 4 tablespoons of sugar). Add in 3 filled syringes too. You will need to do this really slowly and its best to aim at the edge of the inside of the shot glass so that the liquid runs into the mixture rather than straight into the centre. If you aim for the edge and let the liquid drain in then the layers shouldn’t mix together. This is a delicate procedure that can’t be done too quickly.
- Add in 3 filled syringes of the 2nd mixture (ie the bottle with 2 tablespoons of sugar).
- Add in 3 filled syringes of the base mixture (ie the first bottle with no sugar).
- This will complete your sugar water shot glass which will be filled with the different coloured bands.
Here is our final colour of water made with our different mixes.
How to adapt this activity for younger kids
This experiment can take a while to perform and there is a certain element of control and patience that is needed. Some things you can do to adapt this for younger kids
- Use a very small glass to make the density column. We had wanted to use a large container to really see the different bands, however, I quickly realised this was not going to happen with a 3 year old. Hence, we changed to making it in a shot glass. I highly recommend doing the same.
- My child was able to put in the first layer of water. However, the 3 top layers required an adult to put them in. There is too much control that is required to slowly pour the liquid in so that it doesn’t mix.
- Mixing the liquids with a higher amount of sugar takes a fair bit of patience (as in potentially 10 minutes). There isn’t much to do unless you heat the water a bit. However, once done they can feel the resistance of this higher density when compared with a mixture with no sugar.
- If we did it again I would alter my coloured dye. The pink and red were too close in colour and I would substitute one of them for blue.
- We did adapt this activity into a fine motor skill or practising using a syringe. This was a perfect activity to do with younger children and really kept the activity going for much longer than anticipated. We use additional shot glasses to pour all of the water into and, yes, there were some spills! You can double this as a colour mixing activity too.
What is the science behind the rainbow sugar water?
Adding sugar into water changes the density of the water. Liquids that are more dense will sink to the bottom whereas liquids that are less dense will raise to the top. This is why your water with the most sugar will be at the bottom of the rainbow density column whereas the water with no sugar will be at the top and then a gradient appears in the middle.
This is a super simple science activity that you can do at home. It is hands-on and best of all creates a fun colour pattern.