Trouble Loading? What Materials Block WiFi

Girl wearing blue dress using a smartphone.

What materials can prevent  WiFi signals from working effectively?

WiFi may be a very abstract term for young minds. A great way to teach and understand scientific concepts is through imaginative projects - and this is definitely one that the kids will enjoy! Let's take a look at how it works.

Materials Needed

You’ll need a working wireless router, and a WiFi enabled device such as a smartphone. Download a compatible app for measuring WiFi signal. Some apps offer this information in a quality rating, however, try your best to find one that measures in dBm. Before you get going, make sure you are familiar with using the app to measure the WiFi strength and walk around your house to check the WiFi signals in different areas.

On top of this, you'll require the blocking materials. These should be roughly the same size.

Blocking materials:

A metal baking tray.

A tinted glass baking tray.

A wooden chopping board.

A sheet of cardboard.

Aluminium foil.

A container filled with water.

A plastic sheet.

Find a location within your home with a concrete wall (to test the strength from one room with the router, to the other side).


1. First things first, it’s a good idea to give the kids a heads up on what Wi-Fi is. Wi-Fi is the common name for a type of communication that enables electronic devices to exchange data or connect to the internet without the need for wires or cables. Wi-Fi devices do this by using radio waves.

2. Ask the kids to predict which materials they believe can stop WiFi signal from the material options.

3. Discuss with them how you can make this experiment a fair test (for example, using similar sized materials, measuring the strength three times to get an average, measuring the router distance to the blocking material equally).

4. What’s important with however you choose to set up, is to keep the same format each time. Then create a simple recording table with the items listed, trials and the average dBm score.

5. To begin the test, measure the signal strength without implementing any blocking material. This is your experiment’s baseline. Note the signal strength in dBm and write this value under “Trial 1” in the first column of your data table. Repeat this step twice more, for a sum of three trials.

6. You can now get going with measuring with your various materials impact by creating a partition. Be sure not to move the router between trials.

7. Write each material’s result in your table, and at the end compare your results.

Girl and boy playing on tablets.


Discuss your results with the kids. Was it what they were anticipating, or the polar opposite?

You should find that concrete walls hinder the signal strength the most along with aluminium foil and the water-filled container.  This is because concrete is too dense for radio waves to pass through. Water not only blocks waves, but it also absorbs them. Aluminium acts as a conductor of electricity, and it blocks WiFi like a shield. Explain this to the kids. Glass and plastic are not so much of a problem for WiFi signals.

Discuss any ways you could have improved your experiment to have made the experiment fairer. Was including a concrete wall fair? What impact did using wet materials have compared to dry materials? Consider what this tells us about WiFi signals.

How WiFi Works

Depending on the age of your kids, you may wish to explain WiFi further in detail and the wireless network.

To put it simply, a wireless network uses radio waves, in a very similar way to radios,  cell phones and televisions. In fact, signals travelling through a wireless network operate in a very similar manner to a walkie talkie (two-way) radio.

Here's a breakdown of how it works:

1. A laptop's wireless adaptor converts data into a radio signal and transmits thought the air using an inbuilt antenna.

2. A wireless router picks up the signal and interprets the information. The router then sends the information to the internet using a fixed, wired ethernet connection. This works both ways, sending and receiving.

When it comes to the electromagnetic spectrum, WiFi works at the radio frequency level between microwaves and regular radio waves. The majority of wireless networks work on one of two radio frequency bands. These are not the only two bands, but the most commonly found. One band is around approximately 2.4 GHz, and the second is at 5 GHz. What does that mean, though? Quite simply, a hertz is just a measurement unit of frequency. A radio wave is a form of electromagnetic signal created to carry information through the air over considerably long distances.

As mentioned earlier, a wireless router is simply a router that connects to your computer (smart devices) using waves as wireless signals instead of wires. Within the router there is a low-power radio transmitter and receiver, with a top range of around 90 meters or 300 ft. Therefore the router can send and receive internet data to any device in your home that is also wireless access enabled (so each computer using wireless signals has to have both, a radio transmitter and an inbuilt receiver as well).

Mum helping her daughter use a laptop.

Real Life Implications

Think about your home and other spaces such as an office, and how the layout of these rooms may be important to achieve optimum WiFi signal. What about having a large aquarium in an office reception or lots of windows?  How about the furniture itself, such as wooden chairs or metals? It's good to try and generalise the results of your experiment to real life examples and get those young minds problem-solving. There may also be places where you might not want WiFi signals to work!

Two kids playing by the windows.

Further Exploration

There are many variations you can try with this experiment, be creative! What happens when you change surface area, i.e using 10cm, 50cm and 100cm square sheets of aluminium foil? How about several different filled wet and dry containers? You could even add a WiFi booster to see what difference it makes, and try different devices such as a laptop or a tablet.  Connect with your kids and discover for yourself which materials can block WiFi signals!



At Kidadl we pride ourselves on offering families original ideas to make the most of time spent together at home or out and about, wherever you are in the world. We strive to recommend the very best things, that are suggested by our community and are things we would do ourselves - our aim is to be the trusted friend to parents. 

We try our very best, but cannot guarantee perfection. We will always aim to give you accurate information at the date of publication - however, information does change, so it's important you do your own research, double-check and make the decision that is right for your family.  

Kidadl provides inspiration for everything from family days out to online classes, arts, crafts and science experiments. We recognise that not all activities and ideas are appropriate and suitable for all children and families or in all circumstances. Our recommended activities are based on age but these are a guide. We recommend that these ideas are used as inspiration, that ideas are undertaken with appropriate adult supervision, and that each adult uses their own discretion and knowledge of their children to consider the safety and suitability.

Kidadl cannot accept liability for the execution of these ideas, and parental supervision is advised at all times, as safety is paramount. Anyone using the information provided by Kidadl does so at their own risk and we can not accept liability if things go wrong. 

Kidadl is supported by you, the users. When you buy through the links on our site we may earn a commission. As an Amazon Associate we earn from qualifying purchases.

All prices and product availability were correct at the time of publication.

We also link to other websites, but are not responsible for their content.

No items found.
No items found.