In this article we illustrate how one teacher used PhET cannonball simulation as an instructional tool to improve students' algebraic reasoning in a fifth grade classroom. Three instructional phases effective to implementation of simulation included: Free play, Structured inquiry and, Synthesizing ideas.

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### LouAnn H. Lovin

Moving beyond memorization of probability rules, the area model can be useful in making some significant ideas in probability more apparent to students. In particular, area models can help students understand when and why they multiply probabilities and when and why they add probabilities.

### Sandra M. Linder and Amanda Bennett

This article presents examples of how early childhood educators (prek-2nd grade) might use their daily read alouds as a vehicle for increasing mathematical talk and mathematical connections for their students.

### Stephen Phelps

### Edited by Anna F. DeJarnette

A monthly set of problems targets a variety of ability levels.

### P. Reneé Hill-Cunningham

Hundreds of species of animals around the world are losing their habitats and food supplies, are facing extinction, or have been hunted or otherwise negatively influenced by humans. Students learn about some of these animals and explore multiple solution strategies as they solve this month's problems. Math by the Month features collections of short activities focused on a monthly theme. These articles aim for an inquiry or problem-solving orientation that includes four activities each for grade bands K–2, 3–4, and 5–6.

### Stephen Phelps

### Edited by Anna F. DeJarnette

A monthly set of problems is aimed at a variety of ability levels.

### Günhan Caglayan

The Platonic solids, also known as the five regular polyhedra, are the five solids whose faces are congruent regular polygons of the same type. Polyhedra is plural for polyhedron, derived from the Greek poly + hedros, meaning “multi-faces.” The five Platonic solids include the tetrahedron, hexahedron, octahedron, dodecahedron, and icosahedron. **Photographs 1a-d** show several regular polyhedra

### Edited by Anna F. DeJarnette and Stephen Phelps

A monthly set of problems is aimed at a variety of ability levels.

### Michelle L. Meadows and Joanna C. Caniglia

Imagine that you and your language arts colleagues are teaching Edgar Allan Poe's short story, “The Pit and the Pendulum.” This thrilling story takes us to the Inquisition during which a prisoner is surrounded by hungry rats and bound to a table while a large pendulum slowly descends. The prisoner believes that the pendulum is 30-40 feet long and estimates that it should take about 10-12 swings before he is hit, leaving him with about a minute or a minute and a half to escape. Are his estimations correct? If so, will he make it out in time?