Metric 101
It might help to buy some measuring devices. For example, to help you use metric units, you might get a Celsius weather thermometer, a kilogram bathroom scale, a liter water bottle, and a meter stick. If you bike, you can get a bike computer, which will show speed and distance using kilometers if you set it to do so (available at any bike shop). Scales and weather sensors are easily available at Walmart or Target. Meter sticks are available on Amazon and elsewhere.
If you haven't looked at it yet, see the page about how to learn the metric system.