def tokenize_sentence(sentence):
    """
    Tokenize sentence into list of words.

    :param sentence: to tokenize
    :return: the list of words in the sentence
    """
    tokens = []
    token_start = 0
    for i in range(len(sentence)):
        if sentence[i] == ' ':
            tokens.append(sentence[token_start:i])
            token_start = i + 1
        if i == len(sentence) - 1:
            tokens.append(sentence[token_start:i+1])
    return tokens