As the bubbles disappeared at the top of the transparent water-filled tube suffused in green light, three-year-old Sam gazed transfixed, then turned and signed the words "all gone" in Makaton.
Then he pressed and re-pressed the electric pad lying by his knee on the cushioned floor, rapidly changing the light bulb colours in the tube from red to yellow to blue and back to green, as if by magic and sending the air bubbles spiralling to the top.
Like all his classmates at the First Step Opportunity Playgroup in Hornchurch, Essex, Sam, a Downs Syndrome child, was captivated by the interactive multi-sensory room filled with possibilities and ripe for exploring.
Once inside the darkened enclave and supervised by an adult, he played with the fibre-optic curtain, the fire-scene activity board with sirens and lights, the tunnels with mirrors, their entrances fringed with twinkling tinsel, ending with a game of "hidey-boo".
The playgroup for children with special needs is now extremely well equipped. But most of its facilities have been acquired through relentless fund-raising by its parents and organisers in the eight years since its launch as a weekly session in a church hall.
Now based in Dunningford school, it receives a grant of Pounds 30,000 a year from the borough's social services department who regard it as a model of good practice. But its annual running costs are just under Pounds 59,000, so the pressure on parents and staff to raise additional cash is enormous.
It was pioneered by Gill Webb, now its full time co-ordinator, and Margaret Williams, its chairman of trustees and now head of Havering's portage service, in response to the need of a friend with a disabled child.
"She found it hard to find other parents with children in a similar position, and she found it difficult to get the information and support she needed, " Mrs Webb explained. "We launched the mother and toddler group with six participating families and naively thought it would stay like that."
At the last count it had about 70 children and a growing waiting list with enrolments occurring through a process of referral or self-referral. Its children have a wide range of problems such as cerebral palsy, blindness, Downs Syndrome, and learning, behavioural or communication difficulties.
Often they come with their siblings who have no special needs and this early integration has proved enormously beneficial to all the children. Mrs Webb said: "The playgroup capitalises on the children's abilities at an early stage. Sometimes special needs children are overprotected at home and I feel this early intervention gives them a better start.
"In a strange way its very rewarding. I find great encouragement from parents who visibly grow in confidence as a result of coming here with their children. We see them becoming people again. Many of them go through a process of bereavement when they learn they have a child with special needs. They mourn the child they did not have and come to understand the child they have got. Our staff try not to be judgmental and it is wonderful to see the children achieve things when you wonder if they would ever do so."
From its early beginnings, the charity has expanded beyond all expectations. It now runs three mother and toddler groups and three playgroups each week during term time at a parental cost to those who can afford it of Pounds 2 a session. It also holds regular sessions with a paediatrician and a social worker and its parent support group runs once a month.
It has two co-ordinators, a play-leader, a care assistantdriver, a secretary, two escorts for its mini-bus, a music therapist and a dedicated team of about 15 volunteers.
Two days a week some of its children aged from newly born to five see music therapist Jennifer Small who uses instruments to encourage them to communicate. "Music is very much a pre-verbal system," she explained. "It works on methods of communication such as turn taking, setting up interaction by copying rhythms a child makes on one instrument on another, or finishing off phrases of music. It is a very spontaneous way of inter-acting but the children very quickly learn there is a question and answer session going on. Sometimes you can see the penny drop and it is very rewarding.'"