Designing a Sailboat for a Preschool STEM Class


A few weeks ago, I wrote about the process I went through designing a car that kids age 3 to 7 could build in my Family Inventors’ class. Now, for our upcoming session on Wind and Flight, it was time to design a sailboat that they could build.

My criteria:

  • possible for kids as young as 3 to build
  • must be able to float in the water table, and survive getting wet
  • must have a sail that can catch the wind, so kids can use a straw to blow it around (the theme of the week is wind, after all)
  • materials must be affordable, easily accessible, and require a reasonable amount of prep time. Bonus points for re-used / recycled materials
  • if you were planning to have kids float their boats on a stream or lake, you should tie a string on so the boat can’t float away out of reach AND use biodegradable materials in case you lose the boat to the water

I searched the internet (especially Pinterest) for ideas.

Options for boat body

With each of these options, I’ve linked to a webpage that has photos of this kind of boat and info on how to build it.

  • Corks. You could use a single cork – it would be likely to tip over when you blow at the sail, unless you use a weight for a keel – this author appears to have attached pennies to the bottom. Or using two or more corks would increase stability. They can be attached together with rubber bands, hot glue gun, or waterproof tape. I wondered how I would get enough corks for my class, and discovered you can order 100 Recycled Wine Corks for $16
  • Ice Cubes – fun idea for summer, but not something kids can make in class
  • Milk carton with one side cut out. My concerns were: gathering enough cartons, time for cleaning and prepping them, avoiding milk allergens
  • Plastic – I have corrugated plastic from old election signs and such. We used it for our retractable cars. It’s waterproof, flat, with channels for air. I tested it, and it floats well.
  • Pool noodle – Can either do by slicing the noodle into 1-2 inch thick “donuts” or by cutting 5 inch segments and then slicing those in half lengthwise. Potential issues: can you buy pool noodles in November? Also, prep time.
  • Popsicle sticks. Need to have a waterproof glue to fasten them together. If you’re comfortable with your child using a glue gun, that would work fine.
  • Popsicle sticks and corks combined.
  • Sponge. On the upside, zero prep if you use a whole sponge per boat. Downside: cost
  • Styrofoam meat trays. Potential concerns: where would I get them (we don’t cook meat at home), and cleaning to avoid food-borne bacteria. Styrofoam bowls, like you might get ice cream in, are another option.
  • Miscellaneous recycled materials. A great tinkering exercise would be to just gather lots of random materials from the recycling bin: lids, plastic bowls, plastic bottles you can cut the top off of, cups, Styrofoam egg cartons, etc. You’d need to have a way for them to mount the mast for the sails without necessarily cutting a hole in the bottom of the body. Maybe silly putty or a clay that they could stick to body and plant mast in.

I tested the corrugated plastic – it works fine. Takes a little prep work to cut all the bodies, and cut slits in them for masts, but it would be a do-able project.

img_20161116_164733114 img_20161116_164835122

I ended up settling on corks. I haven’t used a glue gun in my class yet, and I know that taping round corks together would be a challenge for my students, so we’ll fasten them together with rubber bands. This also offers the advantage of being able to take them apart and re-use materials for other projects.

Options for mast:

  • Straws, popsicle sticks, dowels, and skewers – we have plenty of each. Because popsicle sticks are flat, they’re easier to fit between corks, so we’ll use those.

Options for sail:

  • Cardstock (works till it gets wet for the first time), craft foam, duct tape (see how to make a duct tape sail), sheets of flexible but strong plastic – I had one sheet of plastic, but have no idea where it came from. I have a laminator, so I tried printing pages with fun designs on them (pirate flags, Viking long boat design, etc) and sealing those in laminator plastic, then cutting out the flags. Sadly, after spending a little time in the water, the little bits of paper exposed at the cut edges would wick in water and the sealed paper would get wet. If I used the laminator in the future, I think I’d just seal close an empty sleeve – a little more flexible than ideal, but it’s an easy source for something workable.

Tutorial for Final Boat Design

Prep: Cut sails. I made 12 sails from a 8.5 x 11 sheet of plastic or of laminated paper. Cut slits big enough to slide popsicle stick through.


Assembly in class

  1. Mount sail on mast by sliding popsicle stick through the slots on the sail.
  2. Rubber band together two corks (cork A and cork B)*
  3. Rubber band together cork B and C.
  4. Put mast between cork B and C, facing toward A.
  5. Rubber band all three corks together.

img_20161116_163236370_hdr img_20161116_163422165_hdr img_20161116_164024347

* Note: you could just rubber band all three together, but they may bunch up into a triangle if you do that.


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