things I wish I would have taken
 

tape- I wish I had masking tape! I reached for it a few times, but didn't have any. I could have taped down the on switch to the provided hair dryer. I could have more eaisly labled my film containers ect..... many uses

Ketchup- I wish I had those small packets we all throw away at fast food joints. I like ketchup and I mean ketchup.

Pencils- The kids beg for them!

gum- they kids crave it

Masking Tape sounds good (hadn't thought of that).
I took stickers which were light and the kids loved them. In a Masai Mara village, I gave them out and at the end of our visit, I saw one boy who had figured out what they were and had them stuck all over his face and arms. Complete with a big grin.
Pencils and Pins are Good.
Balloons are also a big hit.
They love gum, But I was told that we shouldn't take anything with sugar in it as "it is addictive" and there aren't that many dentists around.

A guide told a friend of mine that tourists should NOT give pencils & school supplies to kids directly. Often these kids are skipping school, because they can make money collecting pens and pencils then reselling them!

You would be far better off asking a camp to give school supplies to a local school-- the schools and teachers are typically woefully underfunded.

Also books are very expensive and often difficult to obtain. Even the schools don't have books like dictionaries and atlases. (When I asked a school in Zambia, this is what they requested.)
So skip the pencils and take a couple books. But give them to a school or organization (or someone who will pass them on-- please don't give them directly to kids.

And I agree with Monahan about candy and gum--not a good idea to encourage a sweet tooth and dental decay (or more truancy and begging for the same reasons as the pencils.

We had surgical tape and a roll of plaster tape in our medbag which I chose instead of individual plasters so it could double as regular tape if I needed any and also be used to tape on a dressing if needed.

Wish we'd taken better binoculars and a pair each.

Our mammal and bird books were good but not as good as others we came across.

Yes, surgical tape is great. I used it instead of band-aids/ plasters when I got small cuts, it was great for protecting feet from abrasion/blisters, and it was useful for closing holes in window screens and mosquito netting. Sealed tops on toilettry bottles for return flight home with it too.

It seems stickier than masking tape and has all those additional uses.

Also-- my trusty bandanna (kerchief) was useful at one time or another as a head scarf in the wind, a nose-mouth cover for dust protection and when we were around really smelly carcasses, headband to keep sweat from running into eyes in really hot weather, a back of neck sunburn protector, and a general tie-it-all-together wrap for small stuff in my backpack.

Other small useful things:
1) rubber flipflops for showers and padding around in tents. (Removing boots and sandals worn outdoors keeps dust in tent down and is a big comfort relief for hot tired feet.
3) tiny LED emergency light on a cord-- wore it around my wrist at night so I could always find my way to the loo, and/or find the big flashlight. And it was very useful for seeing camera settings while photographing on night drives.
4)a small bottle of rubbing alcohol/surgical spirits feels great on feet suffering from too much boot time
5)a couple ziplock bags

Yes, I do remember the guides telling us that they sold pens for "other" things. We sent a box back with sorts of USA kid stuff for one of the guide's children which was fun. Hope they enjoyed it. It's hard to know the proper thing to do, but I love the books and I think I can find some small ones that might be fun for some special little ones we might meet.
Thanks for the other suggestions. Schools!
Chuck has amazing "Answers/Repairs" in his DOP kit: Tiny Eyeglass Repair Kit, Super Glue, GooBGone, Eyeglass Cleaner, Dry Cleaning plus all the regular toiletries and it's not even stuffed. I think there's just enough room for Surgical Tape which sounds like it will have many uses.
Oh, I would love a really good "Small" mammal guide. Any suggestions on this?