Pay attention, class! I know that warming temperatures, receding snowline and blooming wildflowers are calling, but let’s review a topic that might save a life: crossing streams and rivers.

As the snowpack melts, the water descends and, depending on the elevation drop, it can move extremely fast. When it looks like a torrent, hikers will unlikely try to cross. But when a river is calmer, that’s when folks get into trouble.

“It’s not moving too fast” and “It doesn’t look deep” might be accurate — or not. Here are a few tips that may keep you out of trouble.

Every year more people are killed in the U.S. while crossing a river than are killed by snake bites.

■ Common sense is better than no sense.

■ The farther into the river, the higher the force; the faster the river, the more force; the higher the river on your body, the more force. If the flow is above your knees, find another spot. Even shallower water can cause you to lose balance if it’s moving fast enough.

■ The fastest part of the river will be just below the top layer, the slowest near the bottom. If you are knee-high in the river, the knees will be taking the most pressure. The higher the water is on your body, the more pressure because there is more body mass under water.

■ Overestimating river speed and depth is better than underestimating. Assume it’s colder, deeper and faster than you imagine, and act accordingly.

■ Water is usually shallower at the widest point of the river.

■ If you have any doubts about safety, don’t cross it.

■ Throw a stick into the water. If it moves faster than you can walk, don’t cross there.

■ Do not cross upstream from trapped trees or branches in the water or overhanging banks. These are called strainers. Do not cross upstream from them because, if you did go down, you could be trapped there by the current and drown, even in relatively shallow water.

■ Barefoot is bad. People take off their shoes because they don’t want to get them wet, not because they’re convinced that barefoot is better. Most outdoors experts say you’re more likely to slip in bare feet or cut them on sharp rocks or slip down a steeply angled rock in bare feet. Keep shoes on for traction.

■ Loosen your pack’s shoulder straps and unbuckle the hip belt. If you fall, ditch the pack.

■ Three legs are better than two, especially if you can’t see what’s under your feet. Use a walking stick, planting it firmly ahead of you on the upstream side. Keep two points on the ground at all times. Think of a tripod’s stability. You may not be able to see the bottom, so you’re feet are walking blind.

■ Cross facing the current while angling slightly downstream for the least resistance. Lean into the current, lift the foot closest to the direction you’re moving and use your walking stick to keep two points on the bottom at all times. Sidestep and shuffle with minimum movement. Don’t take giant steps. Never try to walk normally.

■ It’s not just about deciding where to start; be sure that your exit point is not a steep bank.

■ Pride goeth before the fall. When in doubt, don’t.

■ If you are swept away, point your feet downstream and float on your back, paddling with your hands toward shore. Some suggest trying to stay in a seated position so you can see easier.

Class dismissed.

Sharon Wootton: 360-468-3964 or songandword@rockisland.com.