Double Trouble – Building a Double Helix
The purpose of this exercise is to reinforce the elements learned in module 2 of the programme
in a fun hands-on way. Use the information on genes and DNA from the programme support
pack to revise this subject while children are making the double helix.
DNA is like a chemical language which writes the instruction manual for our bodies. There are 2
single DNA strands wrapped around each other like a spiral stairs in a shape called the double
helix. DNA is made of just 4 chemicals:
A – adenine
T – thymine
C – cytosine
G – guanine
Along this double helix, A always joins with T and C always joins with G. In this lesson, children
will make a DNA double helix model using craft material which can be taken home or displayed in
What you will need
Coloured paper or card, toothpicks, 4 coloured markers, a pencil, sellotape, glue.
It may be helpful to have the paper strips pre-cut.
Questioning, Estimating & Measuring, Recognising Patterns.
1. To make the sides of the DNA ladder, cut two strips of coloured paper that are at least
2ft long and 2in wide. If you don’t have paper that is 2ft long, cut several strips and stick
them together to make this length.
2. To make the rungs of the ladder choose 4 different coloured markers and decide which
colour will represent each chemical base e.g. red = A, blue = T, yellow = C, green = G.
3. Count out 10 toothpicks and colour half of each one in red and the other half in blue
(remember A is always paired with T).
4. Count out another 10 toothpicks and colour half of each one in yellow and the other half
in green (remember C is always paired with G).
5. To construct the double helix, lay each side of the DNA ladder on top of each other and
tape them at both ends.
6. Draw little dots with a pencil along the centre of the DNA ladder at ½ inch intervals.
There should be 20 in total if you make a ladder