Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 90 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.True or false: plugging in the iron is a job for an adult. (a) True (b) False
2. 2.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
3. 3.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) putting the iron away
4. 4.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) yeast (d) a cotton bud
6. 6.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
7. 7.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
8. 8.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a small bowl (d) turmeric powder
10. 10.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) plugging in the iron (d) writing the message
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) a mirror
12. 12.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a mirror (d) a battery cell
14. 14.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) white paper (d) a mirror
16. 16.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) putting the iron away
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) lemon juice (d) a magnet
20. 20.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) the youngest child (d) whoever is fastest
21. 21.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
22. 22.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) a small bowl (d) a magnet
24. 24.True or false: yeast is needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
26. 26.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) heat adds colour (d) the juice scorches first
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a balloon (d) a cotton bud
28. 28.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the iron setting
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
32. 32.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
33. 33.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
34. 34.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
35. 35.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, in the dark (d) yes, if shaken
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) the ironing time (d) how dark the writing is
37. 37.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
38. 38.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
40. 40.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) writing the message (d) reading the message

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