Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 282 · 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 steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) dipping the cotton bud (d) letting the paper dry
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a battery cell (d) a cotton bud
3. 3.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
4. 4.True or false: cutting the lemon is a job a child can do. (a) False (b) True
5. 5.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) dipping the cotton bud (d) reading the message
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) a magnet (d) yeast
7. 7.⚖️ 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 measure it (c) we keep it the same
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a balloon
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
12. 12.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
13. 13.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) cutting the lemon (d) plugging in the iron
14. 14.⚖️ 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
15. 15.🍋 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
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
17. 17.⚖️ 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) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the iron setting (c) the same paper (d) the kind of juice
19. 19.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
20. 20.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
21. 21.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) a small bowl (d) white paper
23. 23.True or false: reading the message is a job for an adult. (a) False (b) True
24. 24.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) dipping the cotton bud
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) a small bowl (d) lemon juice
26. 26.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a balloon (d) an adult with an iron
28. 28.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
29. 29.⚖️ 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
30. 30.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) an adult with an iron (c) a small bowl (d) lemon juice
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same cotton bud (c) how dark the writing is (d) the same paper
33. 33.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) an adult with an iron (d) a balloon
34. 34.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
35. 35.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
36. 36.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
37. 37.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False

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