The learner's preferences
Initially you want to offer the learner a wide variety of objects to gain a sense of his or her preferences and interests. Are there certain qualities that attract the learner? For example, does the learner like shiny things or things that can be bent? Does the learner like the sound of bells or the clunk of walnuts hitting the Resonance Board? Hot, warm or cold objects? Use objects that have interesting properties to the learner and limit objects that are uninteresting or averse. Be careful to avoid the influence of your own biases. Dr. Nielsen's books provide many recommendations and ideas for objects. You may also want to download this list of Attractive Objects from the Texas School for the Blind & Visually Impaired Active Learning Page.
The learner's skill level
If you know what the learner can do with his/her body, especially the mouth, face, hands, arms, trunk, legs and feet, you can select materials that match the learner's developmental skill level. Completing the Functional Scheme assessment will assist in this area.
For example - a child with spastic cerebral palsy may hold his/her hands in a fisted position. Objects selected for positioning by the hands must respond when "pushed" by the fisted hand. Hanging a plastic plate near beads would meet this requirement. Pushing the plate or beads will cause the two items to bang against one another and cause an auditory response. Objects must also be made "graspable." Stringing buttons or beads on elastic, but alternating groups of large and small buttons, allows for parts of the fingers to get caught on the string - thus encouraging accidental "grasping." Placing wax paper or mylar material inside an embroidery hoop, letting the material hang over the rim provide a surface that will "crinkle" when rubbed against.
For example - a child with cerebral palsy who moves his/her feet more than the hands. Objects should also be placed under the feet to encourage exploration. Place a small plate on top of a large plate under the feet - so that when the feet move, the plates rub or bang against one another. Hold a spinning facial brush near the feet- so that movement of the feet will cause the brush to spin at a different rate when pushed against.
A learner just gaining skills in reaching and grasping would experience more success with objects that have slim profiles or where the fingers can easily entangle. A large, slippery object would not be a good choice. Consider which skill area you are focusing on in any environment (fine and gross motor, cognitive, tactile, visual skills, auditory and so forth.)
The number of objects
Think about the number of objects that a typically developing toddler might interact with during the course of a day. It is important the all learners have the opportunity to repeat, compare, experiment and explore. All learners must have the right to choose the materials they would like to interact with. Remember that different objects provide different reinforcers to activity. An Active Learning environment must have large quantities and various types of items. You can't have too many. A learner may focus on only one or two objects at a time, and due to short attention spans may only interact with an item for a few seconds before switching to another object. Other learners may play with one or two objects for extended periods of time. Variety is the key.
What an object is made of
The world is made up of wood, metal, cloth, plastic, rubber and other interesting materials, yet most toys are made of plastic. In order for any learner to understand the characteristics of our world, he/she must interact with objects of various materials. Look for things made from wood, metal, paper, rubber, leather, string, etc. Identify characteristics of objects including smooth, bumpy, soft, hard, cold, warm, squishy, wet, dry, sandy, crinkly, etc. Things that have more interesting tactile, auditory, gustatory or olfactory features are more attractive to a child with visual impairments. Various materials have differing temperatures, density, weight, flexibility and other features that may attract the learner's interest. Some individuals with multiple disabilities may appear to be tactically defensive. Sometimes this is only a result of not having been exposed to a wide variety of interesting textures and materials, or the result of an adult who forces the learner to touch objects whether the learner wants to or not.
What the object can do
An object may have an intended function and yet it can be used in multiple ways. A spoon is used to eat with, but a child can use it to bang on a pot or pan to make music. A corrugated cardboard box can be used to store holiday cards, but a child can scratch his/her fingers over the corrugated cardboard to make a sound while learning to open and close his/her hand. A metal water bottle may be used to drink from, but a child may kick his/her feet or move his/her hands to knock over bottles to feel the vibration as the bottle hits a Resonance Board while learning to move his/her arms and legs.
Can the object be bent? Does it make an interesting noise when banged? Does it have a smell or taste? Look for objects that have multiple features that might appeal to the learner. Think about what the individual currently likes to do with objects. If the learner enjoys poking his or her fingers into holes, find objects with holes. If the learner wants to throw, find lots of objects that can be thrown (balls, small blocks, bags filled with a variety of materials like coffee beans, rice, sand, etc.)