Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 338 · 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 mirror is needed for the secret lemon message. (a) True (b) False
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) how dark the writing is (c) the kind of juice (d) the same paper
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
4. 4.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) ironing the paper
5. 5.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) reading the message (d) ironing the paper
6. 6.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) writing the message
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) yeast (d) turmeric powder
9. 9.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
10. 10.True or false: reading the message is a job a child can do. (a) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a balloon (d) an adult with an iron
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
16. 16.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
17. 17.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a battery cell (d) white paper
18. 18.⚖️ 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 ironing time
19. 19.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
20. 20.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
21. 21.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
22. 22.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
23. 23.True or false: plugging in the iron is a job a child can do. (a) False (b) True
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
25. 25.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) writing the message (d) reading the message
26. 26.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
27. 27.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
28. 28.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
30. 30.⚖️ 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
31. 31.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
32. 32.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) a small bowl (d) a magnet
34. 34.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
35. 35.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
36. 36.True or false: white paper is needed for the secret lemon message. (a) True (b) False
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) an adult with an iron (d) a small bowl
38. 38.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
39. 39.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) ironing the paper (d) putting the iron away
40. 40.⚖️ 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

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