Slowing movements.

Some children are great at the big fast movements, like running, kicking a ball, climbing, and seem well co-ordinated. It can therefore be difficult to understand how come they struggle with controlling a pencil. Just know, that it is easier to make movements fast and big than it is to make small controlled movements. Fine motor movements are a more advanced developmental stage. They require fine motor planning, rather than force and momentum.
Small controlled movements such as are needed for printing require a number of factors to be in  place. 
1. Whole body strength. Challenge the fast moving child to do some movements slower. This requires controlled strength rather than momentum strength. It requires an awareness (maybe unconscious) of the pressure of joints and muscles together, and the sequence of movements.
2. Shoulder strength. The shoulder supports the arm which connects to the hand and fingers. In order the print letters with appropriate pressure and direction, shoulder strength is needed. Encourage the child to carry heavy objects, hang from bars, and be a wheelbarrow.
3. Eye-hand co-ordination.  How is your child at visually tracking? Is the tracking systematic or all over the place? How is the co-ordination needed for constructing with lego? And how is the pressure that is needed to join blocks together - too much? Too little? The use of a variety of construction toys is useful to develop eye-hand co-ordination and pressure.
4. Laterality. Often it is noticed that children who move fast are using their body as one whole object rather than as a body that has 2 halves and a number of parts. Encourage any activity that requires the child to cross the midline.  You might notice that you hand the child things mainly to one side or the middle. Vary it. Can they throw, catch and kick a ball spontaneously in different positions? Practise crossing a foot across the other side of a line while walking. Make a pretend beam with a strip of cardboard - jump side to side, walk along stepping with the opposite foot to the opposite side.
5. Awareness of fine motor movements.  Play with textures increases awareness. Hand play with playdough, sand, finger paint, etc. Drawing in sand or salt gives the child sensory feedback about their movements as long as they use their vision to make the connection. Use of pencils which give sensory or auditory feedback are useful - carbon pencils. 

The ability to make slow movements can be assisted to develop by using the above ideas. Any activities that encourage slow movements without being too challenging are helpful. For example, as in the photo, moving the box that contains little marbles to enable them to sit into small hollows requires small graduated movements. One over sized movement makes all the balls roll out of the hollows.