Building good practice habits takes time and a lot of guidance. These habits will be easier for some students than others. Students will have good days and bad days. This means we need to have a lot of patience, but at the same time we need to constantly remind them how they need to be practicing. With the young beginners (ages 4 to 7 or 8), this means parents are going to be very "hands on" with practicing. I realize most parents don't need anything else added to their to-do list, but helping them out in these beginning years will help them enjoy playing more and build the practice skills they will need when they are older.
As much as possible, try to set aside a specific time to practice. This helps students remember to do their practicing. Try to avoid times when their focus will not be great. My kids are crabby and uncooperative if they have not eaten, so I have to make sure that they have had a snack right after school and before they practice. All this said, I know what real life is like. We sometimes have sports practices at 4pm and sometimes the sports practice is at 7pm. So, our piano practice time does float around a bit. The important thing is do your best to play the instrument every day.
Along with trying to have a set time, make sure your instrument is readily accessible. If you are practicing with a keyboard, keep the keyboard set up on a stand. The goal is to have students play their instrument often and eventually without help. If they walk by their instrument often, they will then hopefully be tempted to play their pieces as they walk by. Or maybe just improvise something when they see their instrument.
In the first lessons, I often have students stand at the instrument rather than having them sit on a bench. Often the students are pretty wiggly (that is ok) so it is safer to have them stand up instead of wiggling themselves off the bench. We also will be moving around the keyboard a LOT, playing low and playing high. They can reach more easily if they are standing. When they start to sit on a bench, it is really important that the bench or chair they use at home is a height that allows their arms to be even with the keys. you can see an ideal position in the picture below. Too high or two low of a bench will make it more difficult for them to develop a relaxed posture at the piano. Also, make sure that the bench is not too close. In lessons, I find students are constantly scooting the bench in too close. I remind them that we don't want T-Rex arms, we want our arms to be out in front of us so we can easily reach high and low keys. In the picture below you can see that this student needs a footstool so that his legs aren't dangling. The footstool helps students to feel like they are not falling off the bench.
At this age, I usually expect students to practice 5-10 minutes a day. Yes, more is definitely acceptable and encouraged. Playing an instrument is very much like playing a sport. Muscles only remember what to do when we have lots of repetition. Practicing is training our muscles. Young beginners do not have long attention spans so I find that breaking up practicing into small time increments is great. For example, have your pianist play one of their pieces two times. Then let them do something else. Maybe a half an hour later ask them to play a different piece two times. I am not saying this is how you MUST do it, but being creative with breaking things up is sometimes better than making them sit at the piano and practicing everything at the same time.
And now some thoughts on technique for young beginners. Young students are still developing fine motor control. We start with learning to use large muscles and we gradually work our way to smaller muscles. This means that in the beginning students might only be playing with one finger. And that is ok. When the arm muscles get more coordinated, we move on to playing with our middle three fingers, when those get coordinated, we move on to playing with our thumbs (1 fingers) and pinkies (5 fingers). If you studied piano as a child, you might have had a teacher that drilled in to you that we focus on perfect hand shape at the beginning. Current pedagogues (myself included) have found that using larger muscles first will help create a more relaxed technique which will encourage healthier playing long term. I will communicate where we are in the process in practice notebooks. Please do not push your child to use all five fingers before they are ready. We want to encourage them to have a healthy body position for a life-time of playing the piano. This body positioning takes time and we move forward in small increments.
Now - what to actually do in your practice time. Your pianist will have a practice notebook. In the notebook, we have a list of pieces which your pianist can play. I would like them to choose 2-3 pieces from the list to play every day. This might mean that you hear the same piece over and over. And over and over. And then you might hear it again. This is absolutely normal and as tiring as it can be for a parent, it is healthy for them. You probably had the same thing happen when you read books to them. (and still read to them.) I think my husband still has The Big Red Barn memorized because he read it so many times. And I remember how we at one time hid the book Take Me Out to the Ballgame because we were so sick of it. That is what you should end up having with their piano pieces. I will try in lessons to review all the pieces, but at this stage, just have them play the pieces they know. As they get older I will make more detailed practice instructions. For now just play.
When you get tired of the pieces, encourage your pianist to mix things up. Sometimes they can sing the words, sometimes they could say the finger numbers or the letter names. Most of the books we use have downloadable audio tracks, they can play along with those. The important thing at this level is to play often and play their pieces many times. Encourage your pianist to make things up at the piano. Let them try out using the pedals. This helps them discover all the different sounds the piano can make.
Hopefully this helps give you an idea of what I expect, happy practicing and always feel free to contact me with questions.