# What crosses a cell boundary?

Explore a membrane's different jobs, compare ways materials cross it, and ask what size and supplied evidence can tell us. You will build explanations, calculate model quantities and revise or keep a claim for a reason.

## Start here

- **Teaching:** [prepare the fortnight](TEACHER.md), then use the [ten complete slots](LESSONS.md) and [thirty adjustable routes](ROUTES.md).
- **Learning:** read the [science cards](SCIENCE-CARDS.md) and choose a response mode for the [daily tasks](LEARNER.md). Words, AAC, a table, a directed sketch and spoken explanation are welcome.
- **Paper aids:** choose a [complete aid and its notice companion](print/README.md). The full text alternatives keep the source conditions and tasks.
- **At home:** try one of [ten free invitations](HOME.md). Each includes its own source and feedback; no experiment or purchase is needed.
- **More to explore:** choose from [ten optional supplements](SUPPLEMENTS.md).
- **Educator feedback:** use the [twenty solved contexts](teacher/WORKED-CONTEXTS.md) and [open answers, descriptive criteria and next teaching](teacher/KEYS-AND-NEXT.md) after an attempt or when intentionally modelling.

## New checks · first work, then new information

For slot 15, give only [E first](checks/first/E.md). Capture the first response before giving [E later](checks/later/E.md). For slot 20, use [F first](checks/first/F.md), then [F later](checks/later/F.md) after collection. Both responses can take extra time. Keep each version and record support. A careful conclusion may deserve to be kept.

These are public teaching checks with open educator answers, not secure examinations. Staff may assign one [unused first recheck](reserve/README.md) after feedback and a delay; its matching later information remains separate until first capture. Do not give keys or unused files with the first encounter.

## A short note for adults

This Queensland General Biology slice offers ten suggested 35-minute slots: 350 minutes about membrane structure, transport, cell size and conceptual diffusion evidence. It follows the introductory cell/organelle starter. The supplied data and geometric models are authored examples; no actual biological investigation is supplied. It does not complete Topic 1, Unit 1 or the course, and has not been classroom piloted. The [source scope and remaining requirements](SOURCE-SCOPE.md), checked 2 October 2026, identify the current QCAA syllabus and access limits. Schools choose pace, actual practical work, safety, access and formal assessment.

Original educational material © NeuroForgeIO Pty Ltd 2026, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). Deliver the [complete offline notice](print/PORTABLE-NOTICE.pdf) with printed aids. Source and font rights remain separate.