A child's ability to properly read and write depends on his/her ability to identify and properly pronounce words within his/her level. Typically in Nigeria, a child in grade 1 is between the age of 5-6. Irrespective of class or age, Learning how to spell is usually fun.
Aside developing the ability to read and write, constant learning of new words also increases one's chances of performing exceptionally in spelling bees.
Here's a list of 100 carefully selected words for 1st graders to help develop their vocabulary as well as prepare them for spelling bees.

Who
Fast
These
Artificial
Religion
Little
Pineapple
Housemate
Snack
Rectangle
Large
Tray
Family
Much
Well
Right
Look
Buy
Yard
Brother
Dish
Temptation
Off
Lot
Forty
Composition
Winter
Light
Could
Take
Says
Double
Monkey
Gave
Speed
Grow
Drive
Lion
Disappear
Nose
Him
Transportation
National
Away
Long
There
Good
Drop
Rock
Yet
Top
Better
New
Shape
Back
Plus
After
Trick
Both
Straw
Mess
Read
Boat
Said
Seven
Blueberry
Every
Motherhood
Song
Send
Call
Sad
Kind
Our
Use
Wednesday
Such
Goat
Deaf
Put
Another
Soon
Animal
Vitamins
Been
Still
Cooked
State
Air
Friend
Account
Clown
Also
Lunch
Money
Night
Movement
Yellow
Natural
Eight
Beak
Now
Again
List
Clock
Tell
Dear
Sea
Might
Barn
Father
Rest
Upon
Line
First
Nine
Quietness
Tore
Cuboid
Seventy
Too
Money
Home
Blend
Would
White
Must
Their
Child
Deliver
Education
Pool
Before
Twelve
Twenty
Umbrella
Went
Sight
Help
Degree
Downstairs
Your
Deep
Write
Path
Cannot
Where
Fatherless
Aeroplane
Think
Fight
Eighteen
Here
Year
Divide
Work
Eleven
Just
Jump
Silly
Second
Between
Tune
Computer
Bolivia
Sphere
Accident
Those
Best
Out
Summer
Made
Drawer
Goes
Place
Dress
Each
Decide
Cool
Drip
Death
Them
Treat
Grapes
Fed
Strawberry
Barbados
Give
Which
Hundred
Lock
Roof
There
Bright
Around
Cold
Birds
Planet
End
Deer
Clean
Bath
Any
Stamp
Loud
Sing
Count
Only
Slid
Town
Why
Even
House
High
Domestic
Grin
Happy
Drain
Most
Europe
Thing
Wish
Dirty
Does
Ask
Dislike
Rabbit
Animal
Samaritan
Great
Always
Very
Fairness
Classroom
Sound
Tuesday
Found
Under
Sister
Wash
Toe
Addition
Soil
Because
Trip
Feed
Slip
Stone
Seem
Drum