Flights from some parts of Europe have been delayed due to particles of rock, sand and glass in the air. See this CBS news report.
Here are some links for you to find out more:
CBBC - What causes volcanoes? You can also find out 2 helpful effects of volcanoes.
ABC - Iceland Volcano: Spewed Ash Grounds Planes
BBC - animated guide to volcanoes
Also don't forget to look at the Rock Cycle post from last week which has a great animation of volcanoes as part of the whole process of how rocks are made from magma.