Frozen Erupting Snow. I don't think I would add the vinegar, leave it for them to play.
'Frozen' Erupting Snow!
Frozen Erupting Snow
MMF #6 -'Frozen' Erupting Snow :http://pagingfunmums.com/2014/07/13/frozen-erupting-snow/
Indoor winter fun can be excellent on a cold, wet day. Give this experiment a try to bring the outside in while staying warm. This is even better if you research why the snow expands when vinegar hits it.
Homemade Glitter Paint
Make 'Frozen' Erupting Snow! pagingfunmums.com
Frozen Erupting Snow 5
Bubbling Erupting Frozen Snow