Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 459 · 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.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a balloon (c) turmeric powder (d) a magnet
2. 2.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) the iron setting (d) how dark the writing is
5. 5.⚖️ 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 ironing time (d) the kind of juice
6. 6.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
8. 8.⚖️ 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
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
10. 10.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
12. 12.🍋 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
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
14. 14.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
15. 15.🔮 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
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
17. 17.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
20. 20.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) ironing the paper (d) writing the message
21. 21.⚖️ 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) how dark the writing is (c) the same paper
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) lemon juice (d) an adult with an iron
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) white paper (c) yeast (d) turmeric powder
24. 24.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) writing the message (d) putting the iron away
25. 25.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
26. 26.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
27. 27.🔮 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
28. 28.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
29. 29.True or false: reading the message is a job for an adult. (a) True (b) False
30. 30.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
31. 31.⚖️ 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
32. 32.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) whoever is fastest (d) the youngest child
33. 33.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
34. 34.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
36. 36.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) letting the paper dry
37. 37.True or false: plugging in the iron is a job for an adult. (a) False (b) True
38. 38.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
39. 39.⚖️ 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 measure it (c) we keep it the same
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) a small bowl (d) lemon juice

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