Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 252 · 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.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
2. 2.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
3. 3.True or false: plugging in the iron is a job a child can do. (a) True (b) False
4. 4.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
5. 5.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
7. 7.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the kind of juice (d) how dark the writing is
9. 9.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
11. 11.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
12. 12.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) letting the paper dry (c) cutting the lemon (d) putting the iron away
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) white paper (d) a mirror
15. 15.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
16. 16.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
17. 17.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
19. 19.🍋 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
20. 20.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
21. 21.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) reading the message
22. 22.🧺 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 magnet
23. 23.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
24. 24.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
25. 25.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) dipping the cotton bud (d) reading the message
26. 26.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a battery cell (d) lemon juice
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
29. 29.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) writing the message
30. 30.True or false: writing the message is a job a child can do. (a) False (b) True
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
32. 32.⚖️ 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 keep it the same (c) we change it
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
34. 34.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
35. 35.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
36. 36.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) letting the paper dry
37. 37.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
38. 38.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) plugging in the iron
39. 39.⚖️ 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 same paper (c) the kind of juice
40. 40.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) dipping the cotton bud (d) reading the message

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