# How to make: tessellating shortbread

## You will need

• 4kg butter
• 6kg flour
• $(2+\varepsilon)$kg sugar
• an oven that has been preheated to 220°C
• a rolling pin
• an oven tray
• a cooling rack
• a knife or cookie cutter

## Instructions

1. Combine 4kg butter, 6kg flour and 2kg sugar in a large bowl with your hands.
2. Roll out the dough on a flat surface.
3. Cut the dough into equally shaped quadrilaterals.
4. Place quadrilaterals on the baking tray and bake for $0.1\dot6$ hours.
5. Place quadrilaterals on the cooling rack, sprinkle with $\varepsilon$kg sugar, leave to cool, then tessellate and eat.

# How to make: a Möbius Surprise

• A3 paper
• scissors
• glue

#### Instructions

1. Cut your A3 paper into 4 strips.

2. Take two strips and glue them perpendicularly to make a cross.

3. Make a Möbius strip with each of the perpendicular strips.

4. Cut along the centre line of one Möbius strip until you get to where you started. Then cut along the other.

5. Be surprised.

# How to make: a catastrophe machine

• cardboard
• scissors
• pins
• rubber bands

#### Instructions

1. Cut out a card circle whose diameter is the length of an unstretched rubber
band. Use pins to attach everything together, as shown above.

2. Drag the lower rubber band around to investigate catastrophe theory.

# How to make: a hyperbolic plane

#### You will need

• triangle paper
• scissors
• sticky tape

#### Instructions

1. Cut out a hexagon and a triangle from the triangle paper.

2. Cut along one of the lines from a corner of the hexagon to the centre.

3. Tape the triangle between the two edges of the cut you just made. There is now more than 360° around the point, so the surface will not be flat.

4. Continue to tape more triangles to the surface, making sure there are always seven triangles at each point.

5. Congratulations! You have made a hyperbolic surface.

# How to make: a slide rule

#### You will need

• scissors
• a printed copy of these images (click to enlarge)

#### Instructions

1. Cut out the two scales.

# Prime jewellery

I was recently given a copy of Crafting Conundrums: Puzzles and Patterns for the Bead Crochet Artist by Ellie Baker and Susan Goldstine. This was pretty exciting for me, as although I knew nothing about bead crochet (I’d never heard of it), I’m a mathematician who enjoys exploring mathematical ideas through craft. So naturally I rushed out and bought lots of beads and thread, and a very tiny crochet hook (1.5mm, if you’re really interested). Continue reading

# How to make: a hexaflexagon

#### You will need

• a long strip of paper a few cm wide, a printed template from here, or your own template from here.
• glue
• a protractor or set square

#### Instructions

1. Fold over the left end of the strip to make an angle of 120°.