When studying the skin, a visual model helps students understand the layers beneath the surface, which they can only imagine as they look at their own epidermis. Building a 3 dimensional skin model will make your science lesson easier to understand. It is unnecessary to buy expensive models of the skin when you can create your own at home is a short period of time.
Rub petroleum jelly on all four sides in the inside of an empty standard envelope box. Cut plastic sheets to cover the bottom and side, making sure the pieces overlap. None of the box should remain bare.
Measure out the amount of water you will need to fill the envelope, following the directions on the container of Plaster of Paris. Pour the water into a bucket.
Measure the amount of Plaster of Paris needed for the project. Sprinkle the plaster into the water, allowing the water to absorb it. When all the plaster is in the water, use a stirring stick to blend it completely. Allow it to sit for one minute before you pour it into the mould.
Place the envelope box on top of paper towels to protect your working surface. Have someone hold the box steady while you fill it with the Plaster of Paris mixture. Shake the box to get bubbles out. Let it set for a minute or two as you hold the sides firm until the plaster begins to set. Let it dry overnight.
Remove the envelope box and the cling film from the dry plaster. Etch a little hole in the top to represent a skin pore. Lay the model down just as if it were an envelope you were about to address, with the long side parallel with the side of the table.
Divide the model into four sections with an etching knife. Starting at the top, where the hair follicles are located, measure down 3/4-inch and 1 1/2-inch. Draw a line all the way across the long length of the model. Measure 1/2-inch from the bottom and etch in one more line across the block. The top two spaces are the epidermis, the large centre section is the dermis and the lower section is the subcutaneous tissue.
Etch the features the students will learn on the skin model. All models should include a hair shaft shaped like a piece of hair that widens as you etch down. Etch from the top. Stop 1/4-inch from the bottom of the subcutaneous layer. Include a sweat pore and gland shaped in a thin tube with a corkscrew at the top. The sweat pore ends with a circle that looks like twisted worms.
Add two networks of blood vessels. The arteriole flows from the heart, the venule are vessels that flow to the heart. Both networks should be etched across the bottom and have vessels that reach up with capillaries branching off from them. The capillaries are thinner than the blood vessels.
Paint the four layers of the skin models, including the sides, back and bottom, making each one a different degree of pink. Mix red and pink in swirls across the bottom to represent a layer of fat. Paint the top a skin tone colour. Make the arteriole and its capillaries red. Paint the venule and its capillaries blue. Paint the hair shaft light brown and the sweat gland light red.
Brush over the entire model with shellac. Once it dries the model will shine. Watch for areas that don't shine and cover them with the brush. Take it to school and use it to enhance your science lesson on skin tissue.
Use removable tabs to label the skin model. Let students use them to practice labelling the sections to practice for a test.
Plaster of Paris can break easily.
Tips and warnings
- Use removable tabs to label the skin model. Let students use them to practice labelling the sections to practice for a test.
- Plaster of Paris can break easily.