Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 805 · 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: a small bowl is not needed for the secret lemon message. (a) False (b) True
2. 2.True or false: ironing the paper is a job a child can do. (a) False (b) True
3. 3.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
5. 5.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
6. 6.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
7. 7.⚖️ 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 same cotton bud (c) the ironing time (d) how dark the writing is
8. 8.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
9. 9.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) reading the message (d) plugging in the iron
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
11. 11.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
12. 12.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) a cotton bud (d) white paper
14. 14.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
15. 15.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
16. 16.True or false: putting the iron away is a job a child can do. (a) True (b) False
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) white paper (d) a small bowl
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
20. 20.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) letting the paper dry (d) writing the message
21. 21.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) plugging in the iron (d) putting the iron away
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
23. 23.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
25. 25.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
26. 26.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
27. 27.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a magnet (d) white paper
29. 29.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) dipping the cotton bud
30. 30.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) turmeric powder
32. 32.True or false: writing the message is a job for an adult. (a) False (b) True
33. 33.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
34. 34.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) cutting the lemon (d) writing the message
36. 36.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a battery cell (c) turmeric powder (d) a balloon
38. 38.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it is sticky (d) it can burn skin
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
40. 40.True or false: ironing the paper is a job for an adult. (a) False (b) True

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