#4 a & b are Tradescantia spathacea or pallida. If you can feel ridges running from stem to leaf tip, a pronounced midrib on the back, it's spathacea. Pallida leaf is flat-feeling, and also purple on top except in too-little light.

Thank you purpleinopp I think that you are right about the #4a & b being Tradescantia spathacea
I looked closer at the leaves; the outside leaves are purple and the inside are green.
http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b653

#5 looks like a Kalanchoe.

susanc #5 maybe Kalanchoe blossfeldiana http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b561

Thank you susanc

My take on them:

1. Callisia fragrans
2. Euphorbia trigona
3. wild guess? maybe a Tulipa?
4. Tradescantia spathacea
5. Kalanchoe, but maybe other than blossfeldiana
6. looks similar to Pedilanthus (to me)
7. Senecio jacobsenii
8. looks most like Kalanchoe carnea 'Modoc' (to me)

Thank you rosemariero6 for your suggestion on my plants. I have added the name of the plants to my photos.