CHEMISTRY QUESTION. How to measure hydrogen gas?

For my school science project I need to find a way to trap hydrogen gas when different metals, (eg, magnesium, calcium, copper) are put into hydrochloric acid. I also need to measure it. I have looked around and have a bit of an idea how to make a practical for this, but it doesn't seem to work for me. If you have any suggestions or practical ideas on how to do this please please please tell me. thankyou :)