# Scaffolding concepts

## Identifying the aim of the visualisation

When creating or improving a visualisation, the most important thing is to clarify what the visualisation is trying to achieve. Please spend some time thinking about the key realisations you want your user to have, and how to place them in a well-ordered manner. The learning process should be as transparent as possible. Think about what the user already knows; what knowledge do you assume? Do they need refreshing on some of the key concepts that'll be used later?

### Example

This is the aim for the 'Orbits' visualisation:

*The aim of this visualisation is to help students understand that gravitational orbits are characterised by the effective potential of the orbit and its total energy. It is intended to give insight into how a change in radial velocity increases the total energy of the orbit, but not the effective potential, whereas a change in tangential velocity increases both the total energy of the orbit and its angular momentum and hence its effective potential.*

The key realisations are explained in the aim. Implicit is the prerequisite knowledge: students should already know the concepts of potential, energy, radial velocity, tangential velocity, and angular momentum. It is important to double-check that these concepts are indeed familiar to the intended student cohort!

## Learning outcomes and visualisation pages

When creating a visualisation, it’s important to think of the key learning steps you want the user to take. To do this, you will need to think about the learner's starting point (what do they know?) and their end point (what is the final aim of the visualisation?). How will you logically lead your learner from the start to the end? Each of the steps will be a learning outcome of the visualisation.

Each key step that could be explored in an independent learning session normally makes up a separate visualisation page. This single page can group together several learning outcomes that are closely linked. If your visualisation incorporates several key steps you should create several visualisation pages which will be grouped in a Collection (read more about Collections here).

* Note that each page should be designed such that it can be used entirely on its own*, without any preceding or following visualisation pages, as it will appear as an individual visualisation on the 'Teach' environment (see Uploading a new visualisation).

An example of a multi-page visualisation collated in a Collection is the ImpVis template demo - it consists of 2 pages that are logically linked: the first explaining the layout of the ImpVis template and the second the individual components in our ImpVis library.

An excellent way to list the key learning steps and to decide how many to have is to write down subtitles that you think each page deserves, where this sub-title describes what that page’s learning step will be in just two or three words. This makes it more evident to the user the main result they need to take from that page and makes the visualisation more comfortable to navigate if they need to return to anything. It also helps you keep track of the structure of the learning journey when creating a visualisation.

### Example

The 'Orbits' visualisation has a final design based on several pages. These are the intended learning outcomes, grouped by page.

*Page 1: Gravitational orbit energy*

*After using this visualisation, students should be able to explain:*

*how total energy relates to orbit type,**that the total energy is the sum of K + U,**the behaviour of K and U for different orbits,*

*Page 2: Orbit dependence on the effective potential*

*After using this visualisation, students should be able to explain:*

*how the intersections of the total energy and the effective potential define the boundaries of the orbit.*

*Page 3: Components of the effective potential*

*After using this visualisation, students should be able to explain:*

*that effective potential has a gravitational contribution and a 'centrifugal' component (dependent on angular momentum),**how the effective potential changes when the angular momentum changes.*

*Page 4: Velocity boosts change the orbit*

*After using this visualisation, students should be able to explain:*

*that total energy has radial KE and tangential KE components that can be varied (but gravitational U is always the same shape)**that an increase in radial KE increases the total energy but leaves effective potential shape the same. Orbit changes because of change of boundaries of orbit.**that an Increase in tangential KE increases total energy AND angular momentum. This changes the effective potential shape and also changes the orbit.*

These pages take the students step by step from their starting point (familiarity with the concepts of potential, energy, radial velocity, tangential velocity, and angular momentum) to their end point: the overall aim of the visualisation.

## Other examples to explore

Khan Academy and Coursera are great places to look for well thought out learning journeys; check these out!