Ok this is a project you can put together for less then 5.00$$ ( I made mine for 1.50 $$ or what not ).
What you need
1.some rigid aquarium tubing ( from your local fish store ) ( length based on the depth of your aquarium )
2. One syringe ( from your local fish store ).
3. And about 3 feet of soft aquarium tubing ( from local fish store ) ( note a good Price for this is about .10$ a foot ).
4. And some time ( about 5 mins )
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Adding the Tubing
Put the tubing onto the plastic syringe( also note the size of the syringe is also the size and quantity of food that you can carry to target feed at any one time.
Step 2: Finish Adding the Tubing
Now slip soft aquarium tubing on to the rigid tubing together end.
Step 3: FEED the Fish ( and What Not )
( please note I do not have a photo of this but I plan on adding one in the near future)
This tool can be used if you A fish including finicky fish soft Corals hard Corals and anything you can think of.