Teach complementary base pairing with this 26-slide, editable PowerPoint for Pearson T Level Science A4.2, with activities and click-to-reveal answers.

This Level 3 Core Biology lesson builds on A4.1 DNA and RNA. Students learn why complementary base pairs keep the DNA double helix a consistent width, then apply the same pairing rules to DNA replication, transcription and translation.

What the lesson covers

• Purines and pyrimidines: identifying the bases by their ring structures.
• Hydrogen bonding: comparing A–T, A–U and G–C and knowing when adenine pairs with thymine or uracil.
• DNA replication and transcription: using a template to work out complementary DNA and RNA sequences.
• Translation: matching an mRNA codon to a tRNA anticodon and explaining how the match helps bring the correct amino acid to the ribosome.

What students do

Students start by interpreting a photograph of a DNA display model. They then sort bases, decide which proposed DNA pairs are valid, build complementary strands and count hydrogen bonds. In the final mixed-up lab record challenge, they distinguish a DNA copy from an RNA transcript and use the RNA sequence to find a matching anticodon. Tasks specify how long to spend, whether to work alone or with others, and what to write.

The PowerPoint includes labelled scientific diagrams, animated worked examples, an 8-mark independent practice task with marking points, and an exit ticket. In Slide Show mode, teachers control when each step or answer appears, so students have time to make a prediction before seeing the feedback.

Allow 65–75 minutes, or split the lesson into two shorter sessions. Speaker notes include timings, suggested questions and common misconceptions. All activities are on the slides, so no separate worksheets or printing are needed.