Building blocks

Why do I want you to teach your students to write complex sentences? Because sentences are the tools students use to build mental models. A student who writes, ‘Oxygen is a gas and magnesium is a metal,’ is merely listing disconnected facts. But a student who writes, ‘Magnesium, a metal, donates an electron whereas oxygen, a non-metal, accepts one,’ is building cognitive links between concepts.

Model building a rich sentence by asking a series of precise, probing questions

Powerful connecting words, like whereas or because, aren’t just grammar. They are precise connectives linking ideas by chronology, cause and effect, similarities and differences. Here are three easy-to-use techniques to help your students write better sentences.

Technique 1: build a better sentence

After you have taught the content, help students put this knowledge in a sentence. Model how to do this using a simple kernel sentence, for example: metals form positive ions.

Write this in the centre of the board. Then, model the process of building a rich sentence by asking a series of precise, probing questions, targeted to prompt specific chemical reasoning:

• Question – when does this happen?
• Example answer – when they react and lose electrons.

This prompts students to think about the process.

• Question – why are these ions positive?
• Example answer – because they have more positive protons than negative electrons.

This focuses learners’ thinking on the cause and probes for the underlying mechanism.

• Question – what happens as a result?
• Example answer – they bond to negative non-metal ions.

This prompts thinking about the next logical step or implication.

These answers transform a fragment of a sentence into a rich, connected concept. To make a sentence, learners need to order the answers and original fragments. You can model this on a visualiser with cards to show them how to move the clauses around to create variations on the same sentence; see examples in the figure below. If you prepare the kernel and unambiguous questions, your students can practise this approach to constructing rich complex sentences.

Technique 2: connecting clauses

Give your students two distinct but related ideas and a choice of conjunctions. This simple task is cognitively powerful. It forces students to think about the relationship between the two ideas and to structure their sentences to reflect that logic.

Technique 3: conjunction gap fills

Provide support structures to help students apply these skills independently. Sentence starters that embed the powerful words help lower the barrier to writing. They provide the grammatical cue, allowing your learners to focus their mental energy on retrieving and explaining the chemical concepts.

Using the concepts from our modelling example, you could provide these starters:

• Metals become positive ions when _______________.
• A metal ion is positive because _______________.
• Metals become positive ions so they _______________.

These scaffolds give students confidence in writing more complex sentences. Consequently, students not only know chemistry, but can also explain it with precision and confidence.

Why teach sentences

Dedicating time to the craft of the sentence is not a detour from the chemistry curriculum. Guiding students to better sentence-building gives them the cognitive tools to build better mental models and to build bridges from isolated facts to interconnected schema. By teaching the language of chemical explanation, we are developing thinkers, communicators and scientists who can articulate not just what they know, but why it matters.