Intervals and endpoints
Plant seedlings on a line or loop and watch gaps light up before the trees count. Endpoint rules become visible instead of memorized.
A tree planting problem is really an interval-counting problem. This game lights the gaps first, then pops trees onto endpoints or around a loop so students can see when to add one, subtract one, or keep the same count.
Aligned with CCSS 3.OA.A.1 and 2.OA.A.1 as an equal-spacing word-problem model.
Interval model
Count the spaces first. Then decide whether the endpoints add, match, or disappear.
6 intervals + 1 = 7 · both endpoints
Olympiad thinking model
Tree Spacing Lab is built for students who need a visual way to decode multi-step puzzle structure. It gives the page a clear search purpose: learn the model, manipulate it, then continue into the matching grade-level practice.
Tree Spacing Lab helps when a student can copy a procedure but cannot explain why it works. The demo slows the idea down into a visible model before sending the learner to guided missions.
Learning goals
How to play
Continue with guided practice
On a line with both endpoints planted, the first and last trees sit at the ends, so n intervals create n + 1 tree positions.
The final interval returns to the first tree. There is no extra endpoint at the end of the line.
When both endpoints are empty, only the inside planting spots remain, so trees = intervals - 1.
Grades 3-5 as an Olympiad-style extension of equal spacing, multiplication, and word-problem modeling.
