Jesus starts off with blessed are those who are poor in spirit for theirs is the kingdom of heaven. Being poor in spirit means that we aren't attached to all the stuff that we have. That you understand that God has given you all the great things or blessings and we should be very thankful and even willing to give them up or share them with others. All our things on earth doesn't matter because we can't take it with us to heaven which will be more amazing than we can imagine.
Have children use white crayons on white paper to draw a picture of a garden full of bumblebees and other friendly critters. Of course, they won't really be able to see their pictures. As they draw, explain that sometimes God's blessings can be invisible in our lives too. For example, we don't always see mercy, or see his peace and strength in our lives, As they finish their drawings, have them use water colors to paint over the whole paper so the picture shows up. Reminding them that when they cover their lives with Jesus, like they cover their paper with paint, a beautiful picture will appear: a picture of God's love and blessing in their lives. As the kids work, ask them to tell you ways that God has blessed them. Encourage them to look for the invisible things, beyond physical stuff.