# Shrink Art and Scale

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

# Shrink Art and Scale

January 28, 2015

While traveling in London, we had a chance to visit the film studio where the Harry Potter movies were made. The coolest part of the tour was seeing a scale model of Hogwarts. When watching the movies, you see many aerial and exterior shots that make you believe Hogwarts is a gigantic place. Imagine the looks on my kids’ faces when they saw what was actually used for filming: a 1:24 scale model that fits in one room!

Seeing every minute detail of Hogwarts shrunken down into a small, exact replica was a great introduction to the concepts of scale and proportionality for my kids. Scale is the ratio of the size of a drawing or model compared with the actual size of the object.

You often see the scale ratio expressed in architectural models, but where else might you find examples? If you own a paper map or a globe, look over it together and find the scale. Close your eyes and point to two spots on the map, then measure the distance between them with a ruler. How far apart are those places in inches? How far apart are they in miles?

While we can’t recreate Hogwarts at home, there is an easy art project you can do to explore scale: shrink art! You can create full-scale artwork of your own design, and then use heat to shrink them down into mini masterpieces.

Shrink art uses a type of plastic known as polystyrene. One of its unusual characteristics is that it has memory. This means when it’s heated, it will return to its original form and shape – just in a smaller version.

You can buy shrink art film at hobby and art supply stores, but chances are you already have some in your home. If you recycle, then you’re probably familiar with the recycling symbol with the number inside on different types of plastics. Polystyrene is also known as #6 plastic, which is often used to make cups, utensils, and food storage containers. Rummage around your plastic food storage trays and look for the #6. If you can find a flat, clean piece, you can use that as well!

### Here’s what you’ll need for your shrunken art:

• * Shrink art film or clean, flat pieces of #6 polystyrene plastic (Note: if you’re using recycled plastic, you’ll want to rough up the surface a bit with some sandpaper to help your colors adhere to the surface).
• * Colored pencils or permanent markers
• * Ruler
• * Scissors
• * Baking sheet
• * Parchment paper
• * Toaster oven or conventional oven

Cut film or sheets of plastic into squares, rectangles or circles of different sizes. Measure them and be sure to note the results. Draw and color your design on the rough side of the plastic. If you want to turn your art into jewelry or key chains (or a dog tag, like the one we made for our puppy!), be sure to punch a hole out before baking.

As you’re designing, ask the kids how much they think the plastic will shrink. Will they be half as small? If they shrink by 25%, is that more or less than half the original size? Do they think it will shrink proportionally, meaning the plastic will shrink the same amount in all directions?

If you’re using shrink film, follow the instructions on the package for heating. If you’re using recycled plastic, preheat the oven to 250 degrees F. Place a sheet of parchment paper on a baking sheet, and place your shrink art on the parchment paper. Leave about 1 inch between each piece.

Place the baking sheet in the oven (if using a conventional oven, turn the oven light on), and turn on your kitchen exhaust fan. Watch your art shrink to a fraction of its original size! The plastic will first start to curl in on itself. Next, it will begin to shrink. As it shrinks, it will flatten out again.

Once the plastic is flat, you can remove the tray from the oven. If any pieces haven’t flattened completely, have an adult place something heavy on top to help it flatten out before cooling.

After your shrink art has cooled, take the measurements again. Did your design shrink in proportion to the original design? Older kids can figure out the percentage of shrinkage by dividing the after-shrinking dimension by the before-shrinking dimension and multiplying by 100. Does the shrinkage rate stay about the same, no matter the size of the original design?

If you find your creativity shrinking and your inner artist needs a break, check out this Bedtime Math Problem about scale. Hungry? Try sizing your food up or down!

Images courtesy of Angie Six