For each of these, try to take multiple shots or ideas. I know there's not a lot of time in your schedule for photography, but see what you can come up with. You should be building a rather full pile of pictures that you can load into your portfolio by now.
Theme - "Trust"
- When you think of a word like "trust", try to imagine what it would be if you had to portray it in a picture. If you were to see a picture, what would make you think "Trust".
Theme - "Cold"
- Cold can be a literal, physical depiction (i.e. a snow scene or someone soaking wet with their breath visible) or it could be a figurative expression (like a stare or a complete disinterest over something that should bring out an emotional response).
Theme - "Strength"
- Like "Cold", "Strength" can be a literal depiction (muscles or someone lifting heavy stuff) or it could be figurative -- an oak tree, a flower pushing through the pavement or an elderly person who has obviously persevered through a rough life.
Theme - "Childhood Memory"
- Childhood memories can be happy, sad, or even scary. They can depict a person, place, item, or even an experience. From something abstract like a clenched hand holding a belt to something more enjoyable like a tree that you helped a parent plant as a little kid. You could depict a favorite toy or a place you liked to play or just something that "takes you back" to when you were little.