Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 861 · 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) yeast (b) lemon juice (c) a small bowl (d) an adult with an iron
2. 2.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron
3. 3.True or false: cutting the lemon is a job a child can do. (a) False (b) True
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) an adult with an iron (d) a small bowl
5. 5.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
7. 7.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
8. 8.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
9. 9.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) a battery cell
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) white paper (d) a magnet
12. 12.⚖️ 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) True (b) False
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a battery cell (d) an adult with an iron
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
15. 15.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the ironing time (d) the same paper
17. 17.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) reading the message
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
19. 19.⚖️ 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
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) lemon juice (d) a mirror
21. 21.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
23. 23.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
24. 24.True or false: yeast is needed for the secret lemon message. (a) False (b) True
25. 25.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
27. 27.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
28. 28.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
30. 30.⚖️ 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 measure it (c) we change it
31. 31.True or false: plugging in the iron is a job a child can do. (a) True (b) False
32. 32.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
33. 33.⚖️ 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
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
35. 35.⚖️ 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
36. 36.⚖️ 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
37. 37.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) an adult with an iron (d) a small bowl
39. 39.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
40. 40.True or false: reading the message is a job a child can do. (a) False (b) True

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