Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 198 · 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 not needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a cotton bud (d) white paper
2. 2.True or false: cutting the lemon is a job a child can do. (a) True (b) False
3. 3.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) reading the message
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
5. 5.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) ironing the paper (d) putting the iron away
6. 6.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
8. 8.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
9. 9.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) letting the paper dry (d) reading the message
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
11. 11.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) ironing the paper (d) putting the iron away
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a magnet (d) lemon juice
13. 13.⚖️ 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
14. 14.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) turmeric powder (d) lemon juice
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
17. 17.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
18. 18.🔮 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
19. 19.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) letting the paper dry
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a mirror (c) a cotton bud (d) an adult with an iron
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
22. 22.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
23. 23.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
25. 25.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) white paper (d) lemon juice
27. 27.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
28. 28.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
30. 30.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
31. 31.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a small bowl (d) a balloon
33. 33.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
34. 34.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
36. 36.True or false: white paper is needed for the secret lemon message. (a) False (b) True
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
38. 38.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
39. 39.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the kind of juice (c) the same paper (d) how dark the writing is

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