Friday 20th September
In our science lesson this week, we wanted to investigate what makes an igneous rock an igneous
rock, a sedimentary rock a sedimentary rock and a metamorphic rock a
metamorphic rock. To do this we started off by each choosing a rock we liked
out of igneous, sedimentary and metamorphic rock selection boxes. Because we
didn’t know which type of rock we’d pick, we then had to do a series of tests
to discover the identity of our rocks. The first test was the hardness test and
this involved us scraping our rock with a lollipop stick to see if any bits
came off. If bits did come off then this told us that our rock wasn’t as hard
as other rocks and this is a trait of sedimentary rocks. Next we tested to see
if our rock was permeable (would let water pass through it). We put a few drops
of water on our rocks and watched to see if the water soaked in. If it did then
our rock was permeable and this is another trait of sedimentary rocks. Yet
another trait of sedimentary rocks is that they fizz (because part of their
make-up is dead creatures) when you put acid on them so we investigated this by
putting a few drops of vinegar on our rocks. The final test was to simply look
carefully at our rocks through a magnifying glass. Igneous, metamorphic and
sedimentary rocks all have detectable appearance features (for example, igneous
rocks often contain crystals) and so it was these features that we were looking
for under our magnifying glasses. Once we had made a choice on which type of
rock we thought our rock was, we brought it back to the front and placed it in
the appropriate selection box. The answers were then revealed.
