Winter is a great time to run germination tests. I like to do this for seeds with a short shelf life or that have been in my stash for so long, I don't remember when they were harvested.
Even if seeds have low germination (less than 50%) we can still plant them, just plant more of them to compensate.
Here is a quick video on how I do my germination test
Pro tip: keep the seeds at the temperature they would grow normally. Tomatoes would like to be warm and dark - so maybe above the fridge. Flax and peas like to grow in cooler conditions, so I keep them on the counter.
Thanks for the reminding and tips. I bought a pack a seeds this spring, 200 of them. I thought there were a lot, until I found out how densely they need to be planted. I could only grow 1 square foot! Nevertheless, I planted most of the seeds more sparsely and harvested 50x more seeds in summer. However the fibers seemed to be too mature and brittle for processing. I will make sure the seeds are properly stored for next year's planting.