The problem with ability grouping too
Some teachers assign pairs by ability - putting strong speakers together and weaker ones together, or deliberately mixing levels. Both approaches have merit in theory, but both carry hidden costs.
Putting weaker students together can reinforce the idea that they're "the low group." Large-scale studies have found that children placed in lower groups show increased emotional and behavioural problems over time. The label sticks, even when it's informal.
Mixing strong with weak can work brilliantly - but only if the stronger student isn't dominating the conversation. Research shows that when the more proficient partner controls the interaction, both students get less out of it. The weaker student stays passive and the stronger one doesn't get challenged.
The real finding from the research? No single pairing is always best. What matters is variation. Sometimes mixed ability is ideal. Sometimes similar levels work better. The power is in rotating - not in finding the one perfect configuration and sticking with it.
Why random is the right default
Random grouping solves the biggest practical problems all at once:
It's fast. No agonising over who goes where. A shuffle takes five seconds.
It's fair. No student can complain about favouritism - it's visibly random. Nothing to argue about.
It builds community. After a few weeks, every student has worked with every other student. Cliques soften. The room feels more connected.
It removes your bias. Teachers are human. We have unconscious preferences about which students "work well together." Randomisation takes that variable out of the equation.
It stays fresh. The same pair doing the same activity every week gets stale. New partners bring new energy, new accents, and new ideas.