Ahead of the lesson, make simple contour maps on half sheets of paper, each a little different (e.g. some have one or more steeper slopes, for older students some can have two peaks). (attached file of ideas coming soon). Make a duplicate copy of each contour map.
With students, look at a topographic map that shows the height of land in different colours e.g. this map of Hawaii: https://commons.wikimedia.org/wiki/File:Hawaii_Island_topographic_map-f…
Ask students how many mountains there are on the map (two or four), point out the colour changes as the height changes.
Then point out the lines between the colours - these are called contours and show where the land gets higher.
Then look at a map that shows only the contours, lacking colour changes with height e.g. this map of Cypress Mountain: https://maps-vancouver.com/vancouver-topographic-map
Show them the contours and tell students that they show how high the land is, and their spacing tells us how steep or gentle a slope is, and where there are river valleys and plateaus.
Tell students they will make their own model of a mountain from a simple contour map.
Demonstrate the activity, before students run it themselves (pairs work well):
Cut out a contour map around its outer edge, while the other student rolls out about half of the play dough to about 1cm thick, or until it is large enough to fit the contour map on it.
Lay the cut piece (showing the shape of the lowest level of the contour map) on the play dough and use the butter knife to cut out the shape. Lay the shape to one side of the mat.
Now, cut out around the next smallest contour line, and roll out a new piece of play dough (students can switch roles). Lay the (now smaller) contour map on the new rolled-out play dough and cut out the (new) shape. Lay the new play dough shape over the first one, using the duplicate contour map, to show where to lay the second layer over the first layer.
Repeat with the following contour lines, cutting out their shapes in play dough, and using the un-cut contour map to show how to align the layers on the growing mountain.
(For older students, more complex mountains with two peaks can be made.) If there is any doubt how to align one layer on the next, use a toothpick to help:
Before picking up the first paper contour cut-out, stick a toothpick through the paper and into the play dough in several places. When subsequent layers are made, push the toothpick through the same holes in the paper into the rolled-out play dough before removing the paper. The toothpick holes in the play dough can be aligned to place each layer in its proper position.
Once all the pieces are assembled into a mountain, students can bring their mountain to a central area where they are placed for display, with the duplicate contour map alongside. As new mountains are added, place them next to the previous ones, and place the corresponding contour maps in equivalent positions in their own next door area. The growing landscape of model mountains will be reflected in the growing contour map assembly next to it.
(As students understand the relationship between the growing mountain landscape and the adjacent contour map, they can help direct where to place the contour maps correctly.)
As a class, look at the landscape and the contour maps. Refer back and forth while discussing and highlighting these features of a contour map:
When lines are close together, a slope is steep.
When lines are far apart, a slope rises gradually.
A valley forms between slopes.
Optional: smooth out the slopes of the mountains, to make the landscape more realistic-looking, but emphasizing that the contour lines can still describe the slopes of the mountains (but just not in-between the lines, hence more lines make it more accurate).
As a class, look at a real contour map (preferably in an area that students are familiar with e.g. the same Cypress mountain map with the Sea-to Sky highway) and try to read the mountains (which sides are steep as they have contours close together), the gentle slopes and the plateaus.
Now show students where the rivers come down and how the contours are shaped in river valleys.
Optional: ask students to return to their mountain models, and make a river valley, curving the layers to show how the contours bend backwards where there is a river.
Optional and advanced: Students make a new contour map of their mountain with their new river valleys included.