Unit planning based on a theme involves teachers selecting a theme such as autumn, designing activities to address as many curricular areas as possible that can impinge on ‘autumn’, and collecting and organizing the needed resources. Sometimes only one theme is used and sometimes sub-themes are included under the main theme. A book, a subject area (e. g. science), physical things (e. g. fish, water), actions and processes (e.g. writing, swimming), settings (e. g. the land of the pharaohs), events (e. g. Christmas), seasons (e. g. autumn), and so on can be used as themes.

Theme-based unit planning normally consists of a series of activities that are somehow connected to the theme. For example, the theme of autumn provides the thread that connects reading and writing (autumn stories and words), mathematics (story problems about autumn), science (what happens to leaves and what animals do in autumn), social studies (autumn festivals and what farmers do in autumn), music (autumn songs), art (autumn scenes and colours), etc.

While theme-based planning can be useful for teaching mathematics, there are at least two important concerns with it. First, a theme-based unit may be plagued by the potpourri problem. This problem arises when teachers manage a theme so as to provide for only a loose and trivial sampling of topics from various subject areas. This can easily result in disconnected and insignificant learning in a particular subject area(s). One way to address the potpourri problem is to plan backwards. This involves setting clear learning goals ahead of time and then determining the theme and activities that should lead to the desired outcomes in meaningful ways.

With respect to learning mathematics, the potpourri problem often means that old skills and understandings are maintained in superficial ways and that new skills and understandings are seldom developed. The following example illustrates this.

While children might learn that spiders have eight legs, the linkage to adding and subtracting is strained. And, the arithmetic work is unlikely to be sufficiently challenging. The activity is not a good example of integration in the sense of making meaningful connections between mathematics and spiders. The activity does not involve spiders to generate any reason for learning any new mathematics. Nor does it involve using mathematics to learn about spiders in any important way. Mathematics could be better connected to spiders. In arithmetic, children could engage a data management project that involves counting the number of spider webs in their yards and the number of insects caught in them. The data could be used to address questions about the impact of spiders on insect populations. Learning new things about addition could ensue. In geometry, spider webs could be investigated. Drawing them, identifying patterns in them, and making webs out of string could be involved.

A second concern with theme-based planning concerns the amount of attention paid to children’s interests and experiences. A theme is an organizing device for planning. In practice, the theme itself may interest students but the mathematics-oriented activities may not. For example, children might find the theme of bears interesting. However, they might not be interested in a data management activity that involves sorting pictures of bears that were cut out from magazines and graphing the results. Under these conditions, children are not likely to see the relevance of the mathematics in relation to the theme. Nor are they likely to engage in any important mathematical learning.