An experiment from earlier in the year that I finally got round to posting. We saw various pins on Pinterest raving about a "homemade lava lamp". Using just coloured water, oil and Alka Seltzer you create your own lava lamp effect in a bottle. Not sure what I expected but I was a little disappointed the effects did not quite live up to some of the photos in the pins. B really enjoyed doing it though and has requested a repeat of the activity.