When teaching children how to rehearse (i.e., repeat, practice) new information, such as lists of items or vocabulary words, help them organize the items into a form that has meaning. For example, they can imagine a baseball field and place each item in a position (e.g., item one is on first base). Mnemonics (see Resources section) also help organize information, such as the name "Roy G. Biv" to remember the order of the colors in a spectrum (red, orange, yellow, green, blue, indigo, violet).
Making memory-building a game will increase children's interest in the activity. One game is to place about seven items on a tray, let the children look at the items for a few seconds, then cover the items with a cloth and ask them how many of the items they can remember. To help them improve, next time show them how to see the items in relation to each other (e.g., the paperclip is near the point of the pencil).
Variations of this game include secretly removing one of the items before showing the tray to the children again and then asking which item is missing.
You can also play a similar game at the beach by drawing shapes or pictures in the sand, then smoothing over the sand (or allowing the water to wipe it away) and asking which drawings the children can remember.
There are also short-term memory games and tests available online at sites such as Neuroscience for Kids (see Resources section), including Simon Says games, during which children observe which shapes on the screen light up and then attempt to repeat the pattern by clicking on the shapes in the order they recall.
Another activity that increases short-term memory---even though many of us were taught to not do it in school---is to doodle while listening to a lesson being taught or listening to a story being read aloud. According to research conducted by Jackie Andrade, a psychology professor, and reported by Alix Spiegel on National Public Radio in 2009, people who doodle while listening to long or otherwise boring information keep their brain active and end up recalling about 29 percent more of what was said than people who do not doodle.