Hi Margaret,
I also love that fact about stars – and since stars last for billions of years, most of the nearby ones are still there.
With the volcano activity, asking
Ask the children what they think will happen when you mix the baking soda and vinegar together.
will only build on their science if they have some background in mixing and chemical reactions.
I’d be inclined to do the demonstration as an amazing prompt – and then ask the children how they think they could make the eruption bigger/ or quicker / or last longer… and let then apply their new understanding in a testable way.
I did this with my Brownie Guides last year- and many of these 8-10 year old girls had seen a similar eruption, either in school or from a book/video. It meant we could have fun building on their ideas – so we made a paper volcanoes and looked at the difference the volcano shape made to the eruption.