Plastic Bottle Geometry Set

As a team of college students, we undertook this project as a part of our college studies.

The aim of the project was to create a system that allows kids to make shapes (both 2-D and 3-D) using old plastic bottles, for educational purposes.

The goal was that by creating this system, kids will gain a better and deeper understanding of geometry and basic concepts like angles, 2-D, and 3-D shapes. Not only does our project improve their understanding of geometry but has many other benefits including; problem-solving skills, maths skills and it promotes creativity, due to the DIY aspect of the project.

We explored many different mechanisms used for the construction of these shapes and always kept in mind our target audience, young students, so we had to make the system easy to make with safe accessible tools.

This instructable shows you how to make a full geometry set which can make 8 different triangles, 3 different squares, 3 different rectangles, 12 different regular polygons, 3 different rhombi, 3 different parallelograms, 1 cube, and 5 cuboids. The full set consists of 24 'strips', 4 'struts', and 8 bottle cap joiners.

In this instructable, we will share our final design, as well as tips and tricks to make your geometry set work seamlessly.

8 x 2 L Plastic bottles

Scissors

Sharpie

Ruler

Box Cutter

1. Set up a working area with plenty of space.
2. Clean your bottles by removing the labels and giving them a rinse.
3. Have your scissors, ruler, marker, box cutter, and plastic bottles ready to go.

1. Measure 5 cm from the bottom and top of the bottles and make a mark around the bottles using your marker.
2. Use the box cutter to poke a hole in the bottles on these lines to start your cut.
3. Cut along your marker lines using the scissors.
4. Place the middle part of the bottle on its side and cut it down vertically.

You now have the 8 tops and the 8 bottoms of the bottles and a rectangle of plastic from each!

1. On the rectangular parts measure, six strips each 4.5 cm wide, and mark with your marker.
2. Cut along your lines with the scissors.

Tip: To save time cut one strip to the correct width and use it as a guide for the rest.

You now have 24 strips of plastic, each 4.5 cm wide

1. Measure 8 strips to be 21.5 cm in length.
2. Measure 8 strips to be 19.5 cm in length.
3. Measure 8 strips to be 12.5 cm in length.
4. Mark these measurements with your marker.
5. Cut with your scissors.

1. Take one of the shortest strips.
2. Measure 1 cm down from the top and draw a line across the width of the strip.
3. Measure 3.5 cm down from the top and draw a line across the width of the strip.
4. Measure 1 cm in from the sides and draw two lines vertically between the other horizontal lines.
5. Repeat this on the other end of the strip.
6. Cut out this marked square.
7. Use this strip as a template for the rest of the holes.
8. Line the template strip up to the corners of the other strips and trace the square onto them.
9. Cut the squares out of each strip.

Tip: When cutting the square out it is easier to fold the plastic widthways and lengthways, at the marked square, and then cut with the scissors.

1. Round the corners of the strips using the scissors.
2. Wipe any marker off the strips so your final shapes will look great !

You now have 24 strips in total (8 of each length)

1. Take the remaining four center parts that you cut in step 2.
2. Measure 17 cm across the width, mark, and cut using the scissors.
3. Roll it up tight to form a plastic tube.

Tip: Use plastic with a corrugation, it will make your final 3-D shapes stronger.

1. Cut the necks off the bottles using the scissors.

You now have a full set: 24 strips (8 of each length), 4 struts and 8 caps.

To make 2-D shapes simply connect the strips together by over lapping them at different angles, depending on the shape that you wish to make, and putting a neck through the hole and screwing on the cap.

From the strips, struts and caps you have, you can make:

• squares
• rectangles
• rhombuses
• parallelograms
• triangles (right angled, isosceles, equilateral and scalene)
• pentagons
• hexagons
• heptagons
• octagons

To make 3-D shapes simply make two squares or rectangles and connect the opposite bottle caps to each other with the struts.

From the strips, struts, and caps you have, you can make:

• cubes
• cuboids