Characteristics of Children with ADHD: Overview
The child with ADHD is more spirited, difficult to control and active. When these children wake up in the morning, their “internal engines” are already revved up and running, even before they sit down for breakfast. Their activity levels have them bouncing from one activity to the next and they tend to create a trail of disorder behind them.
As these children enter school, their desks are a whirlwind of papers, books, crayons, pencils and trash. The important items, such as homework assignments, get lost in the maelstrom. Their parents receive calls from the school on a regular basis, with the message that the child has forgotten lunch money or the permission slip for a field trip.
Impulsive and Aggressive
The characteristics of children with ADHD are many. Before anything else, remember that the child with ADHD is a sensitive individual who picks up on the negative impressions others may develop.
Attention deficit hyperactivity disorder makes it difficult for the child to calm down and curb impulses. Instead, as soon as a thought develops, it is acted upon, whether it is to run to the pencil sharpener or water fountain for the sixth time in the morning. The child can’t form the concept that the incessant physical activity disrupts classroom instruction. 
In the same fashion, these children may also be aggressive. ADHD makes it impossible for them to temper their interactions with others –– they want what they want when they want it; this single-minded focus causes them to miss social, facial and behavioral cues when they hurt or offend someone else, and because of this, they may not appear to experience guilt.
Because of their impulsivity, aggression and seeming lack of remorse, children with ADHD may not be very popular with their schoolmates or age peers. 
Lack of Self -Control
Because of how ADHD affects the brain, children with the disorder have to seek frequent stimulation. This “need for speed” drives them to act, as if with no self-control. For preschool children, this is demonstrated as acting out, taking toys from other children, hitting and argumentativeness.
During instruction an ADHD child’s motor continues to run, making it difficult to control behaviors and actions. When the child can’t hold back any longer, he or she says or does something completely unexpected. 
Have Difficulty with Instructions
The child with ADHD can’t act on a laundry list of instructions –– especially if the instructions are complex. These children are frequently visual thinkers, needing time to develop a mental image related to the instruction; it is hard for them to follow a long list of things to be done.
Let's consider an instruction like this: “Becky, please take your plate to the sink and rinse it. When you’ve done that, make sure all of your books and homework are in your backpack, then brush your teeth, get your jacket, hat and mittens and meet me in the front room.” As Becky hears this, her attention wanders after her mother says, “and rinse it.” While the plate gets (somewhat) rinsed, her mother is thinking, “OK, she’ll meet me in the front room in a few minutes, ready to go to school.” Meantime, Becky has skipped to her room and is now engrossed with her favorite toy and several minutes pass.
Mother comes to Becky’s room, exasperated because they are late to leave for school and work. She gets even more upset when she sees her daughter playing rather than getting ready. 
A common characteristic of children with ADHD is that they have a difficult time sitting still, whether at home, playing on the bedroom floor or during Circle Time at school. Knees and legs are twitching and wiggling, arms are moving, sometimes in someone else’s face. The child’s head is bobbing, occasionally to an inaudible rhythm.
Older children with ADHD frequently jump out of their seats to sharpen a pencil, talk to a classmate, grab a book, get a drink of water, or visit the bathroom.
At home, these children willingly sit at the dinner table, but because of the need for frequent movement, the glass of milk topples over and the spoonful of vegetables becomes a full catapult, moving across the dinner table, raining broccoli or corn as it moves. 
Acts First, Thinks Later
Children diagnosed with ADHD can’t hold back, no matter how hard they try. If they know the answer to, “What is 3 times 5?” they frequently blurt out,“15!” before the teacher has a chance to pick a student to answer.
In social situations, this tendency loses more friends for the child as he or she interrupts classmates and friends, trying to say what they are thinking before the thought disappears forever. On the playground, these children can’t wait for their turn. They are the ones, shifting from foot to foot impatiently or bouncing restlessly as the line moves, ever so slowly.
This is the child who, feeling repentant climbs a tall tree to retrieve a friend’s possession, despite the fact that he or she stands a good chance of falling from the tree. An ADHD child doesn’t think of the possible consequences of their actions. 
 Dr. Grant L. Martin. Characteristics and Causes of Attention Deficit Disorders. Troubled With, retrieved from https://www.troubledwith.com/ParentingChildren/A000000367.cfm?topic=parenting+children%3A+adhd
 Attention Deficit and Hyperactivity Disorder. Early Intervention Support, retrieved from https://www.earlyinterventionsupport.com/diagnosis/List/Attention-Deficit.aspx