He was unhappy with his stepson for staying up past his bedtime.
To punish the seven-year-old, he posed a series of maths questions to the boy.
And for every wrong answer, he would pinch the boy on the inner thighs.
The "test" ended with the boy suffering bruises on his inner thighs over an area half the size of a sheet of A4 paper.
The man also slapped his wife and his four-year-old stepdaughter.
Yesterday, he was jailed six months for one charge of ill treatment of a child, with another charge taken into consideration for sentencing.
We are not naming anyone to protect the children's identity.
Court papers said the accused, a 36-year-old who installs bird netting for a living, lived with his wife, who has two children from her previous marriage.
At about 9pm on Aug 5, 2014, the accused walked past his stepchildren's bedroom when he noticed his stepson fidgeting under the pillow.
It turned out that the boy was playing with a headband with lights instead of sleeping.
Unhappy, the man decided to test the boy with some maths questions.
Other than pinching him, the stepfather also yelled at the boy. This drew the attention of the boy's mother, who rushed over to find her son crying and unable to answer the questions.
The stepfather went on to slap the boy's face two to three times.
When his wife intervened, he slapped her as well before leaving the bedroom.
The boy's mother calmed the boy down and put him to bed.
His injuries came to light the next day, when his teacher noticed he had difficulty walking and found heavy bruising on his inner thighs.
The boy was taken to National University Hospital and found to have two large patches of bruises, with one measuring 14cm by 13cm.
The hospital's Children Emergency Department informed the police about the child abuse.
Court papers said the accused had also slapped his stepdaughter and pinched her armpits in February 2014.
Yesterday, the boy's stepfather appeared in court and admitted to one count of ill-treating the young boy under the Children And Young Persons Act, with one similar charge taken into consideration.
Defence counsel James Joseph said in mitigation that his client was remorseful and had gone overboard in trying to discipline the child.
He added that his client was surprised his actions had caused such serious injuries.
District Judge Ng Peng Hong said this was a very serious offence as the victim was young and vulnerable.
The judge said the court needed to deter like-minded individuals from inflicting unnecessary ill treatment to these young and vulnerable victims.
The maximum punishment for abusing a child is a four-year jail term with a fine of up to $4,000.
Lawyers: Never use excessive force
Disciplining your child is no easy task.
And should you turn to physical punishments, make sure they are never excessive and that you are in control, experts told The New Paper.
"Many parents physically discipline their children, but the threshold is crossed when there's an injury," said lawyer Rajan Supramaniam.
Lawyer Gloria James-Civetta said physical punishments turn into abuse when parents put their child in great pain.
"While there are no parental guidelines on how to discipline your child, the force used should never be excessive that it leaves the child in great pain," she explained.
Dr Carol Balhetchet, clinical psychologist and senior director for youth services at the Singapore Children's Society, said she does not advocate physical punishments.
First, there is a likelihood of causing serious physical injury to the child, she said.
More importantly, it could leave the child emotionally or mentally scarred from the experience.
"Repeated physical punishment or abuse will build fear, shame and anxiety in the child and cause him to lose confidence and become an empty shell," said Dr Balhetchet.
"Furthermore, you can't see the emotional scars until later on, when they go for psychiatric assessments."
She added that for physical punishments to be effective, they have to be administered in increasing doses each time - which may then cross the boundary and become child abuse.
All the experts TNP spoke to said there are better methods in disciplining children.
Madam Tracy Tan, part-time childcare teacher and mother of two children in their 20s, said communication is key in shaping a child's behaviour, not caning or shaming them.
"Children today are very intelligent. If your child did something wrong, talk to him, communicate and educate him," she added.
"Get him to learn what he did wrong - that's most effective."
Dr Ken Ung, senior consultant child, adolescent and adult psychiatrist with Adam Road Medical Centre, said parents could punish their child via other methods such as removing the child's television or computer privileges, or grounding the child.
"Very importantly, the punishment should be a form of training and send a message," he explained.
"When you use physical punishments, the means could be so extreme that the child becomes confused to what's the message.
"In that case, the purpose of the punishment is lost."
But in the event that parents still wish to turn to physical punishment, Dr Ung said it should be used only as a last resort.
"Even so, make sure you use the minimum amount necessary and that you stay in control," he added.
"The unwritten rule of physical punishments is that they should never leave an injury or a permanent mark on the child."
A woman who gave birth to her daughter out of wedlock was jailed seven months on Oct 24, 2012, for caning, kicking and throwing a chair at her child.
The 25-year-old mother also admitted to repeatedly caning, slapping, kicking and using clothes pegs to pinch her daughter's back in February and March 2011.
Assistant Public Prosecutor Raja Mohan said the child's biological father left the accused - who has two other daughters with a 31-year-old former boyfriend - after she became pregnant.
The accused repeatedly abused the child over trivial matters while she and the victim were living with another boyfriend.
A father who punished his two young sons by beating and burning them was jailed 48 months' and given eight strokes of the cane on Feb 17, 2011.
The accused had pleaded guilty to nine counts: Four of using a heated substance to burn the buttocks of his two sons and five of ill-treating them.
The two children, then aged five and two, suffered significant and numerous injuries. The older child had at least 10 injuries while the younger one had 35.
Deputy Public Prosecutor Lee Zu Zhao said the accused used wicked and perverse means such as a heated object purportedly to discipline them.
Had a social worker not gone to the flat a second time to check, the abuse would have gone on indefinitely, he added.
This article was first published on January 19, 2016.
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