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“Epoch of Bubbles” Activity


This activity is an analogy of how reionisation occurs during the early Universe, and how we expect to observe it. It is not a perfect analogy, but is intended merely to give an idea of the concepts involved in an interactive and fun way.

The below video is a simulation cube of the reionisation process during the early Universe. The neutral hydrogen (red) is being transformed into ionised hydrogen (transparent) by the new stars (white) that have formed from the hydrogen clouds collapsing due to gravity. This process took about 1 billion years, but in the simulation is sped up to 20 seconds.

Target audience:

This activity is best suited to kindergarten and primary school aged children (ages 4 – 12). The wide range is due to the level of complexity that can be delved into about the science involved. If you wish to use this activity in your classroom and would like more information or have feedback on this activity, please contact our outreach coordinator.


  1. Bubble solution (which you can make from equal amounts of soap and water),
  2. Non-toxic paint or food dye,
  3. A small container with an opening about 7cm in diameter,
  4. Some kind of tube and air source (eg. straws and people’s lungs, or a fish-tank pump and tube),
  5. Print outs of the ASTRO 3D “Epoch of Bubbles” activity sheet on thick paper (available for free below),
  6. A tray, towels, and other methods for cleaning up and/or minimising mess (having the activity outside on grass helps with this).

Set up:

Set up for this activity can be as simple or complex as you want it to be. The key features are:

  1. Place some bubble/paint solution in a container,
  2. Blow bubbles in the solution until the bubbles appear over the edge of the container,
  3. Lay the grid of the activity sheet over the bubbles for half a second.

And that’s it!

The below video shows the set up for the fish-tank option, but if you’re using straws it will be very similar. Note that the containers used in the video have holes cut out in the top half, facing away from the camera, that the tubes from the fish-tank are feeding into. Only a small amount of bubble/paint solution is put into the containers so as to reduce the risk of spillages.

Safety and other considerations:

  1. If you are using straws that students blow into, make sure no one shares their straws.
  2. This activity may result in spillages that could cause someone to trip and injure themselves. Make sure everyone is aware of safety before setting up, and appropriate procedures are in place to minimise risk.
  3. Please avoid using disposable straws. Straws and other single-use plastic items are causing our marine environments many issues. If you need to use straws instead of the fish-tank option, please use cardboard or re-usable metal or wood straws instead of plastic.

Activity sheet:

This activity sheet is double sided, and we suggest printing on 220gsm paper, as normal printer paper (150gsm) is very thin and tears easily when wet. If you are getting these printed by a professional printing press, make sure they DO NOT add a water-resistant coating to the paper (or it won’t work!).