Mixing liquids is usually quite straight-forward, with the multiple substances combining together due to how liquid particles work. But what happens when different densities factor in? That’s what we’re going to explore in the Layered Liquids experiment. There’s a number of different liquids you can try out for this, making it a very flexible experiment. You will need:

• A see-through glass
• Water
• At least 2 of the following: honey, maple/corn syrup, vegetable oil, dish soap, rubbing alcohol, milk, lamp oil
• Food colouring (optional)
• Glitter (optional)
• Small items to drop into the glass (e.g. coins, bottle caps, grapes)

Method:

• First things first, prepare everything you’re going to be adding into the glass. Depending on how many different liquids you’ll be using will influence how much you need to pour into the glass. For example, if you’re using 3 different liquids (including water), you’ll first want to start off by filling up your glass one-thirds of the way with water. Don’t worry if your ratios are slightly off, the experiment will still work no matter how much liquid you pour in.
• Once the water has been added, next up is to fill the glass with all the other liquids you’ve prepared, one at a time. If you’ve decided to use food colouring, that’ll need to go in first. It’s job is to just colour the water and make it more visually appealing. The same applies for the glitter. After that, any of the liquids can be added in any order.
• While doing this, be sure to keep in mind how much liquid your glass can hold and keep to your ratios. Because of the density of each substance added, you should already see the liquids separated into different layers. For example, honey will usually be at the bottom while lamp oil is commonly on the top layer.
• After every liquid has been added, you can now drop in small items to see what layer they will stop at. For example, a cog or screw will sink right to the bottom while a ping-pong ball will float on top. And that’s the Layered Liquids experiment – Play around with dropping in various small objects to your heart’s content!

The Science Bit: Simply put, the liquids you have poured into your glass separate into different layers because of their contrasting densities. Heavy liquids such as honey and maple/corn syrup sink to the bottom while lighter ones such as vegetable oil and lamp oil float to the top. These differences in weight create a layered column effect in the glass. The same applies to the objects dropped in. Once an object reaches a layer that is denser than itself, it will float above that layer.